Linaro-mm-sig

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5 participants
2541 discussions

Re: [Linaro-mm-sig] [PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes

by Liam Mark

On Mon, 21 Jan 2019, Andrew F. Davis wrote: > On 1/21/19 2:20 PM, Liam Mark wrote: > > On Mon, 21 Jan 2019, Andrew F. Davis wrote: > > > >> On 1/21/19 1:44 PM, Liam Mark wrote: > >>> On Mon, 21 Jan 2019, Christoph Hellwig wrote: > >>> > >>>> On Sat, Jan 19, 2019 at 08:50:41AM -0800, Laura Abbott wrote: > >>>>>> And who is going to decide which ones to pass? And who documents > >>>>>> which ones are safe? > >>>>>> > >>>>>> I'd much rather have explicit, well documented dma-buf flags that > >>>>>> might get translated to the DMA API flags, which are not error checked, > >>>>>> not very well documented and way to easy to get wrong. > >>>>>> > >>>>> > >>>>> I'm not sure having flags in dma-buf really solves anything > >>>>> given drivers can use the attributes directly with dma_map > >>>>> anyway, which is what we're looking to do. The intention > >>>>> is for the driver creating the dma_buf attachment to have > >>>>> the knowledge of which flags to use. > >>>> > >>>> Well, there are very few flags that you can simply use for all calls of > >>>> dma_map*. And given how badly these flags are defined I just don't want > >>>> people to add more places where they indirectly use these flags, as > >>>> it will be more than enough work to clean up the current mess. > >>>> > >>>> What flag(s) do you want to pass this way, btw? Maybe that is where > >>>> the problem is. > >>>> > >>> > >>> The main use case is for allowing clients to pass in > >>> DMA_ATTR_SKIP_CPU_SYNC in order to skip the default cache maintenance > >>> which happens in dma_buf_map_attachment and dma_buf_unmap_attachment. In > >>> ION the buffers aren't usually accessed from the CPU so this allows > >>> clients to often avoid doing unnecessary cache maintenance. > >>> > >> > >> How can a client know that no CPU access has occurred that needs to be > >> flushed out? > >> > > > > I have left this to clients, but if they own the buffer they can have the > > knowledge as to whether CPU access is needed in that use case (example for > > post-processing). > > > > For example with the previous version of ION we left all decisions of > > whether cache maintenance was required up to the client, they would use > > the ION cache maintenance IOCTL to force cache maintenance only when it > > was required. > > In these cases almost all of the access was being done by the device and > > in the rare cases CPU access was required clients would initiate the > > required cache maintenance before and after the CPU access. > > > > I think we have different definitions of "client", I'm talking about the > DMA-BUF client (the importer), that is who can set this flag. It seems > you mean the userspace application, which has no control over this flag. > I am also talking about dma-buf clients, I am referring to both the userspace and kernel component of the client. For example our Camera ION client has both a usersapce and kernel component and they have ION buffers, which they control the access to, which may or may not be accessed by the CPU in certain uses cases. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

5 years, 11 months

Re: [Linaro-mm-sig] [PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes

by Liam Mark

On Mon, 21 Jan 2019, Andrew F. Davis wrote: > On 1/21/19 1:44 PM, Liam Mark wrote: > > On Mon, 21 Jan 2019, Christoph Hellwig wrote: > > > >> On Sat, Jan 19, 2019 at 08:50:41AM -0800, Laura Abbott wrote: > >>>> And who is going to decide which ones to pass? And who documents > >>>> which ones are safe? > >>>> > >>>> I'd much rather have explicit, well documented dma-buf flags that > >>>> might get translated to the DMA API flags, which are not error checked, > >>>> not very well documented and way to easy to get wrong. > >>>> > >>> > >>> I'm not sure having flags in dma-buf really solves anything > >>> given drivers can use the attributes directly with dma_map > >>> anyway, which is what we're looking to do. The intention > >>> is for the driver creating the dma_buf attachment to have > >>> the knowledge of which flags to use. > >> > >> Well, there are very few flags that you can simply use for all calls of > >> dma_map*. And given how badly these flags are defined I just don't want > >> people to add more places where they indirectly use these flags, as > >> it will be more than enough work to clean up the current mess. > >> > >> What flag(s) do you want to pass this way, btw? Maybe that is where > >> the problem is. > >> > > > > The main use case is for allowing clients to pass in > > DMA_ATTR_SKIP_CPU_SYNC in order to skip the default cache maintenance > > which happens in dma_buf_map_attachment and dma_buf_unmap_attachment. In > > ION the buffers aren't usually accessed from the CPU so this allows > > clients to often avoid doing unnecessary cache maintenance. > > > > How can a client know that no CPU access has occurred that needs to be > flushed out? > I have left this to clients, but if they own the buffer they can have the knowledge as to whether CPU access is needed in that use case (example for post-processing). For example with the previous version of ION we left all decisions of whether cache maintenance was required up to the client, they would use the ION cache maintenance IOCTL to force cache maintenance only when it was required. In these cases almost all of the access was being done by the device and in the rare cases CPU access was required clients would initiate the required cache maintenance before and after the CPU access. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

5 years, 11 months

[PATCH v4 0/4] locking, drm: Fix ww mutex naming / algorithm inconsistency

by Thomas Hellstrom

This is a small fallout from a work to allow batching WW mutex locks and unlocks. Our Wound-Wait mutexes actually don't use the Wound-Wait algorithm but the Wait-Die algorithm. One could perhaps rename those mutexes tree-wide to "Wait-Die mutexes" or "Deadlock Avoidance mutexes". Another approach suggested here is to implement also the "Wound-Wait" algorithm as a per-WW-class choice, as it has advantages in some cases. See for example http://www.mathcs.emory.edu/~cheung/Courses/554/Syllabus/8-recv+serial/dead… Now Wound-Wait is a preemptive algorithm, and the preemption is implemented using a lazy scheme: If a wounded transaction is about to go to sleep on a contended WW mutex, we return -EDEADLK. That is sufficient for deadlock prevention. Since with WW mutexes we also require the aborted transaction to sleep waiting to lock the WW mutex it was aborted on, this choice also provides a suitable WW mutex to sleep on. If we were to return -EDEADLK on the first WW mutex lock after the transaction was wounded whether the WW mutex was contended or not, the transaction might frequently be restarted without a wait, which is far from optimal. Note also that with the lazy preemption scheme, contrary to Wait-Die there will be no rollbacks on lock contention of locks held by a transaction that has completed its locking sequence. The modeset locks are then changed from Wait-Die to Wound-Wait since the typical locking pattern of those locks very well matches the criterion for a substantial reduction in the number of rollbacks. For reservation objects, the benefit is more unclear at this point and they remain using Wait-Die. Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Gustavo Padovan <gustavo(a)padovan.org> Cc: Maarten Lankhorst <maarten.lankhorst(a)linux.intel.com> Cc: Sean Paul <seanpaul(a)chromium.org> Cc: David Airlie <airlied(a)linux.ie> Cc: Davidlohr Bueso <dave(a)stgolabs.net> Cc: "Paul E. McKenney" <paulmck(a)linux.vnet.ibm.com> Cc: Josh Triplett <josh(a)joshtriplett.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Kate Stewart <kstewart(a)linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne(a)nexb.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: linux-doc(a)vger.kernel.org Cc: linux-media(a)vger.kernel.org Cc: linaro-mm-sig(a)lists.linaro.org v2: Updated DEFINE_WW_CLASS() API, minor code- and comment fixes as detailed in each patch. v3: Included cleanup patch from Peter Zijlstra. Documentation fixes and a small correctness fix. v4: Reworked the correctness fix.

5 years, 12 months

Re: [Linaro-mm-sig] [PATCH] staging: android: ion: add buffer flag update ioctl

by Laura Abbott

On 1/3/19 5:42 PM, Zengtao (B) wrote: >> -----Original Message----- >> From: Laura Abbott [mailto:labbott@redhat.com] >> Sent: Thursday, January 03, 2019 6:31 AM >> To: Zengtao (B) <prime.zeng(a)hisilicon.com>; sumit.semwal(a)linaro.org >> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>; Arve Hjønnevåg >> <arve(a)android.com>; Todd Kjos <tkjos(a)android.com>; Martijn Coenen >> <maco(a)android.com>; Joel Fernandes <joel(a)joelfernandes.org>; >> devel(a)driverdev.osuosl.org; dri-devel(a)lists.freedesktop.org; >> linaro-mm-sig(a)lists.linaro.org; linux-kernel(a)vger.kernel.org >> Subject: Re: [PATCH] staging: android: ion: add buffer flag update ioctl >> >> On 12/23/18 6:47 PM, Zengtao (B) wrote: >>> Hi laura: >>> >>>> -----Original Message----- >>>> From: Laura Abbott [mailto:labbott@redhat.com] >>>> Sent: Friday, December 21, 2018 4:50 AM >>>> To: Zengtao (B) <prime.zeng(a)hisilicon.com>; >> sumit.semwal(a)linaro.org >>>> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>; Arve >> Hjønnevåg >>>> <arve(a)android.com>; Todd Kjos <tkjos(a)android.com>; Martijn >> Coenen >>>> <maco(a)android.com>; Joel Fernandes <joel(a)joelfernandes.org>; >>>> devel(a)driverdev.osuosl.org; dri-devel(a)lists.freedesktop.org; >>>> linaro-mm-sig(a)lists.linaro.org; linux-kernel(a)vger.kernel.org >>>> Subject: Re: [PATCH] staging: android: ion: add buffer flag update >>>> ioctl >>>> >>>> On 12/19/18 5:39 PM, Zengtao (B) wrote: >>>>> Hi laura: >>>>> >>>>>> -----Original Message----- >>>>>> From: Laura Abbott [mailto:labbott@redhat.com] >>>>>> Sent: Thursday, December 20, 2018 2:10 AM >>>>>> To: Zengtao (B) <prime.zeng(a)hisilicon.com>; >>>> sumit.semwal(a)linaro.org >>>>>> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>; Arve >>>> Hjønnevåg >>>>>> <arve(a)android.com>; Todd Kjos <tkjos(a)android.com>; Martijn >>>> Coenen >>>>>> <maco(a)android.com>; Joel Fernandes <joel(a)joelfernandes.org>; >>>>>> devel(a)driverdev.osuosl.org; dri-devel(a)lists.freedesktop.org; >>>>>> linaro-mm-sig(a)lists.linaro.org; linux-kernel(a)vger.kernel.org >>>>>> Subject: Re: [PATCH] staging: android: ion: add buffer flag update >>>>>> ioctl >>>>>> >>>>>> On 12/19/18 9:19 AM, Zeng Tao wrote: >>>>>>> In some usecases, the buffer cached attribute is not determined at >>>>>>> allocation time, it's determined just before the real cpu mapping. >>>>>>> And from the memory view of point, a buffer should not have the >>>>>> cached >>>>>>> attribute util is really mapped by the cpu. So in this patch, we >>>>>>> introduced the new ioctl command to target the requirement. >>>>>>> >>>>>> >>>>>> This is racy and error prone. Can you explain more what problem >> you >>>>>> are trying to solve? >>>>> >>>>> My use case is like this: >>>>> 1. There are two process A and B, A takes case of ion buffer >>>>> allocation, >>>> and >>>>> pass the buffer fd to B, then B maps and uses it. >>>>> 2. Process B need to map the buffer with different cached attribute >>>>> for different use case, for example, if the buffer is used for pure >>>>> software algorithm, then we need to map it as cached, otherwise >>>>> non-cached, and B needs to deal with both cases. >>>>> And unfortunately the mmap syscall takes no cached flags and we >>>>> can't decide the cache attribute when we are doing the mmap, so I >>>>> introduce new the ioctl even though I think the solution is not as >> good. >>>>> >>>>> >>>> >>>> Thanks for the explanation, this was about the use case I expected. >>>> I'm pretty sure I had this exact problem once upon a time and we >>>> didn't come up with a solution. I'd still like to get rid of uncached >>>> buffers in general and just use cached buffers (see >>>> http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/201 >>>> 8-N >>>> ovember/128842.html) >>>> What's your usecase for uncached buffers? >>> >>> Some buffers are only used by HW, in this case, we tend to use >> uncached buffers. >>> But sometimes the SW need to read few buffer contents for debug >>> purpose and no synchronization is needed. >>> >> >> If this is primarily for debug, that's not really a compelling reason to >> support uncached buffers. It's incredibly difficult to do uncached buffers >> correctly I'd rather spend effort on making the cached use cases work >> better. >> > No, not only for debug, I meant if the buffers are uncached, the SW will only mmap > them for debug or even don't need to mmap them. > So for the two kinds of buffers: > 1. uncached: only the HW need to access it, the SW don't need to mmap it or just for debug. > 2. cached: both the HW and the SW need to access it. > The ION is designed as a generalized memory manager, I think we should cover as many > requirements as we can in the ION design, so I 'd rather that we keep the uncached support. > And I don’t quite understand the difficulty you mentioned to support the uncached buffers, would > you explain a little more about it. > We end up with aliasing problems. Each kernel page still has a cached mapping so it's very difficult to keep the two mappings in sync. https://lore.kernel.org/lkml/20181120164636.jcw7li2uaa3cmwc3@DESKTOP-E1NTVV… This thread does a better job of explaining the problem and the objections to uncached buffers. And if the software never touches the buffer, why does it matter if the buffer is uncached? Laura > Thanks > Zengtao > >> >>>> >>>>>> >>>>>>> Signed-off-by: Zeng Tao <prime.zeng(a)hisilicon.com> >>>>>>> --- >>>>>>> drivers/staging/android/ion/ion-ioctl.c | 4 ++++ >>>>>>> drivers/staging/android/ion/ion.c | 17 >>>> +++++++++++++++++ >>>>>>> drivers/staging/android/ion/ion.h | 1 + >>>>>>> drivers/staging/android/uapi/ion.h | 22 >>>>>> ++++++++++++++++++++++ >>>>>>> 4 files changed, 44 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/staging/android/ion/ion-ioctl.c >>>>>>> b/drivers/staging/android/ion/ion-ioctl.c >>>>>>> index a8d3cc4..60bb702 100644 >>>>>>> --- a/drivers/staging/android/ion/ion-ioctl.c >>>>>>> +++ b/drivers/staging/android/ion/ion-ioctl.c >>>>>>> @@ -12,6 +12,7 @@ >>>>>>> >>>>>>> union ion_ioctl_arg { >>>>>>> struct ion_allocation_data allocation; >>>>>>> + struct ion_buffer_flag_data update; >>>>>>> struct ion_heap_query query; >>>>>>> }; >>>>>>> >>>>>>> @@ -83,6 +84,9 @@ long ion_ioctl(struct file *filp, unsigned int >>>>>>> cmd, unsigned long arg) >>>>>>> >>>>>>> break; >>>>>>> } >>>>>>> + case ION_IOC_BUFFER_UPDATE: >>>>>>> + ret = ion_buffer_update(data.update.fd, data.update.flags); >>>>>>> + break; >>>>>>> case ION_IOC_HEAP_QUERY: >>>>>>> ret = ion_query_heaps(&data.query); >>>>>>> break; >>>>>>> diff --git a/drivers/staging/android/ion/ion.c >>>>>>> b/drivers/staging/android/ion/ion.c >>>>>>> index 9907332..f1404dc 100644 >>>>>>> --- a/drivers/staging/android/ion/ion.c >>>>>>> +++ b/drivers/staging/android/ion/ion.c >>>>>>> @@ -436,6 +436,23 @@ int ion_alloc(size_t len, unsigned int >>>>>> heap_id_mask, unsigned int flags) >>>>>>> return fd; >>>>>>> } >>>>>>> >>>>>>> +int ion_buffer_update(unsigned int fd, unsigned int flags) { >>>>>>> + struct dma_buf *dmabuf; >>>>>>> + struct ion_buffer *buffer; >>>>>>> + >>>>>>> + dmabuf = dma_buf_get(fd); >>>>>>> + >>>>>>> + if (!dmabuf) >>>>>>> + return -EINVAL; >>>>>>> + >>>>>>> + buffer = dmabuf->priv; >>>>>>> + buffer->flags = flags; >>>>>>> + dma_buf_put(dmabuf); >>>>>>> + >>>>>>> + return 0; >>>>>>> +} >>>>>>> + >>>>>>> int ion_query_heaps(struct ion_heap_query *query) >>>>>>> { >>>>>>> struct ion_device *dev = internal_dev; diff --git >>>>>>> a/drivers/staging/android/ion/ion.h >>>>>>> b/drivers/staging/android/ion/ion.h >>>>>>> index c006fc1..99bf9ab 100644 >>>>>>> --- a/drivers/staging/android/ion/ion.h >>>>>>> +++ b/drivers/staging/android/ion/ion.h >>>>>>> @@ -199,6 +199,7 @@ int ion_heap_pages_zero(struct page >> *page, >>>>>> size_t size, pgprot_t pgprot); >>>>>>> int ion_alloc(size_t len, >>>>>>> unsigned int heap_id_mask, >>>>>>> unsigned int flags); >>>>>>> +int ion_buffer_update(unsigned int fd, unsigned int flags); >>>>>>> >>>>>>> /** >>>>>>> * ion_heap_init_shrinker >>>>>>> diff --git a/drivers/staging/android/uapi/ion.h >>>>>>> b/drivers/staging/android/uapi/ion.h >>>>>>> index 5d70098..99753fc 100644 >>>>>>> --- a/drivers/staging/android/uapi/ion.h >>>>>>> +++ b/drivers/staging/android/uapi/ion.h >>>>>>> @@ -74,6 +74,20 @@ struct ion_allocation_data { >>>>>>> __u32 unused; >>>>>>> }; >>>>>>> >>>>>>> +/** >>>>>>> + * struct ion_buffer_flag_data - metadata passed from userspace >>>>>>> +for update >>>>>>> + * buffer flags >>>>>>> + * @fd: file descriptor of the buffer >>>>>>> + * @flags: flags passed to the buffer >>>>>>> + * >>>>>>> + * Provided by userspace as an argument to the ioctl */ >>>>>>> + >>>>>>> +struct ion_buffer_flag_data { >>>>>>> + __u32 fd; >>>>>>> + __u32 flags; >>>>>>> +} >>>>>>> + >>>>>>> #define MAX_HEAP_NAME 32 >>>>>>> >>>>>>> /** >>>>>>> @@ -116,6 +130,14 @@ struct ion_heap_query { >>>>>>> struct ion_allocation_data) >>>>>>> >>>>>>> /** >>>>>>> + * DOC: ION_IOC_BUFFER_UPDATE - update the specified ion >> buffer >>>>>> flags >>>>>>> + * >>>>>>> + * Takes an ion_buffer_flag_data structure and returns the result >>>>>>> +of the >>>>>>> + * buffer flag update operation. >>>>>>> + */ >>>>>>> +#define ION_IOC_BUFFER_UPDATE _IOWR(ION_IOC_MAGIC, 1, \ >>>>>>> + struct ion_buffer_flag_data) >>>>>>> +/** >>>>>>> * DOC: ION_IOC_HEAP_QUERY - information about available >>>> heaps >>>>>>> * >>>>>>> * Takes an ion_heap_query structure and populates >> information >>>>>> about >>>>>>> >>>>> >>> >

6 years

Re: [Linaro-mm-sig] [PATCH] staging: android: ion: move map_kernel to ion_dma_buf_kmap

by Laura Abbott

On 12/24/18 12:19 AM, Qing Xia wrote: > Now, as Google's user guide, if userspace need clean ION buffer's > cache, they should call ioctl(fd, DMA_BUF_IOCTL_SYNC, sync). Then > we found that ion_dma_buf_begin_cpu_access/ion_dma_buf_end_cpu_access > will do ION buffer's map_kernel, it's not necessary. And if usersapce > only need clean cache, they will call ion_dma_buf_end_cpu_access by > dmabuf's ioctl, ION buffer's kmap_cnt will be wrong value -1, then > driver could not get right kernel vaddr by dma_buf_kmap. > The problem is this subtly violates how dma_buf is supposed to work. All setup is supposed to happen in begin_cpu_access. I agree calling map kernel each time isn't great but I think this needs to be worked out with dma_buf. Thanks, Laura > Signed-off-by: Qing Xia <saberlily.xia(a)hisilicon.com> > --- > drivers/staging/android/ion/ion.c | 46 ++++++++++++++++++--------------------- > 1 file changed, 21 insertions(+), 25 deletions(-) > > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c > index 9907332..f7e2812 100644 > --- a/drivers/staging/android/ion/ion.c > +++ b/drivers/staging/android/ion/ion.c > @@ -303,45 +303,47 @@ static void ion_dma_buf_release(struct dma_buf *dmabuf) > static void *ion_dma_buf_kmap(struct dma_buf *dmabuf, unsigned long offset) > { > struct ion_buffer *buffer = dmabuf->priv; > + void *vaddr; > > - return buffer->vaddr + offset * PAGE_SIZE; > + if (buffer->heap->ops->map_kernel) { > + mutex_lock(&buffer->lock); > + vaddr = ion_buffer_kmap_get(buffer); > + mutex_unlock(&buffer->lock); > + if (IS_ERR(vaddr)) > + return vaddr; > + > + return vaddr + offset * PAGE_SIZE; > + } > + > + return NULL; > } > > static void ion_dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long offset, > void *ptr) > { > + struct ion_buffer *buffer = dmabuf->priv; > + > + if (buffer->heap->ops->map_kernel) { > + mutex_lock(&buffer->lock); > + ion_buffer_kmap_put(buffer); > + mutex_unlock(&buffer->lock); > + } > } > > static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, > enum dma_data_direction direction) > { > struct ion_buffer *buffer = dmabuf->priv; > - void *vaddr; > struct ion_dma_buf_attachment *a; > - int ret = 0; > - > - /* > - * TODO: Move this elsewhere because we don't always need a vaddr > - */ > - if (buffer->heap->ops->map_kernel) { > - mutex_lock(&buffer->lock); > - vaddr = ion_buffer_kmap_get(buffer); > - if (IS_ERR(vaddr)) { > - ret = PTR_ERR(vaddr); > - goto unlock; > - } > - mutex_unlock(&buffer->lock); > - } > > mutex_lock(&buffer->lock); > list_for_each_entry(a, &buffer->attachments, list) { > dma_sync_sg_for_cpu(a->dev, a->table->sgl, a->table->nents, > direction); > } > - > -unlock: > mutex_unlock(&buffer->lock); > - return ret; > + > + return 0; > } > > static int ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf, > @@ -350,12 +352,6 @@ static int ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf, > struct ion_buffer *buffer = dmabuf->priv; > struct ion_dma_buf_attachment *a; > > - if (buffer->heap->ops->map_kernel) { > - mutex_lock(&buffer->lock); > - ion_buffer_kmap_put(buffer); > - mutex_unlock(&buffer->lock); > - } > - > mutex_lock(&buffer->lock); > list_for_each_entry(a, &buffer->attachments, list) { > dma_sync_sg_for_device(a->dev, a->table->sgl, a->table->nents, >

6 years

Re: [Linaro-mm-sig] [PATCH] staging: android: ion: add buffer flag update ioctl

by Laura Abbott

On 12/23/18 6:47 PM, Zengtao (B) wrote: > Hi laura: > >> -----Original Message----- >> From: Laura Abbott [mailto:labbott@redhat.com] >> Sent: Friday, December 21, 2018 4:50 AM >> To: Zengtao (B) <prime.zeng(a)hisilicon.com>; sumit.semwal(a)linaro.org >> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>; Arve Hjønnevåg >> <arve(a)android.com>; Todd Kjos <tkjos(a)android.com>; Martijn Coenen >> <maco(a)android.com>; Joel Fernandes <joel(a)joelfernandes.org>; >> devel(a)driverdev.osuosl.org; dri-devel(a)lists.freedesktop.org; >> linaro-mm-sig(a)lists.linaro.org; linux-kernel(a)vger.kernel.org >> Subject: Re: [PATCH] staging: android: ion: add buffer flag update ioctl >> >> On 12/19/18 5:39 PM, Zengtao (B) wrote: >>> Hi laura: >>> >>>> -----Original Message----- >>>> From: Laura Abbott [mailto:labbott@redhat.com] >>>> Sent: Thursday, December 20, 2018 2:10 AM >>>> To: Zengtao (B) <prime.zeng(a)hisilicon.com>; >> sumit.semwal(a)linaro.org >>>> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>; Arve >> Hjønnevåg >>>> <arve(a)android.com>; Todd Kjos <tkjos(a)android.com>; Martijn >> Coenen >>>> <maco(a)android.com>; Joel Fernandes <joel(a)joelfernandes.org>; >>>> devel(a)driverdev.osuosl.org; dri-devel(a)lists.freedesktop.org; >>>> linaro-mm-sig(a)lists.linaro.org; linux-kernel(a)vger.kernel.org >>>> Subject: Re: [PATCH] staging: android: ion: add buffer flag update >>>> ioctl >>>> >>>> On 12/19/18 9:19 AM, Zeng Tao wrote: >>>>> In some usecases, the buffer cached attribute is not determined at >>>>> allocation time, it's determined just before the real cpu mapping. >>>>> And from the memory view of point, a buffer should not have the >>>> cached >>>>> attribute util is really mapped by the cpu. So in this patch, we >>>>> introduced the new ioctl command to target the requirement. >>>>> >>>> >>>> This is racy and error prone. Can you explain more what problem you >>>> are trying to solve? >>> >>> My use case is like this: >>> 1. There are two process A and B, A takes case of ion buffer allocation, >> and >>> pass the buffer fd to B, then B maps and uses it. >>> 2. Process B need to map the buffer with different cached attribute >>> for different use case, for example, if the buffer is used for pure >>> software algorithm, then we need to map it as cached, otherwise >>> non-cached, and B needs to deal with both cases. >>> And unfortunately the mmap syscall takes no cached flags and we can't >>> decide the cache attribute when we are doing the mmap, so I introduce >>> new the ioctl even though I think the solution is not as good. >>> >>> >> >> Thanks for the explanation, this was about the use case I expected. >> I'm pretty sure I had this exact problem once upon a time and we didn't >> come up with a solution. I'd still like to get rid of uncached buffers in >> general and just use cached buffers (see >> http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2018-N >> ovember/128842.html) >> What's your usecase for uncached buffers? > > Some buffers are only used by HW, in this case, we tend to use uncached buffers. > But sometimes the SW need to read few buffer contents for debug purpose and > no synchronization is needed. > If this is primarily for debug, that's not really a compelling reason to support uncached buffers. It's incredibly difficult to do uncached buffers correctly I'd rather spend effort on making the cached use cases work better. Thanks, Laura >> >>>> >>>>> Signed-off-by: Zeng Tao <prime.zeng(a)hisilicon.com> >>>>> --- >>>>> drivers/staging/android/ion/ion-ioctl.c | 4 ++++ >>>>> drivers/staging/android/ion/ion.c | 17 >> +++++++++++++++++ >>>>> drivers/staging/android/ion/ion.h | 1 + >>>>> drivers/staging/android/uapi/ion.h | 22 >>>> ++++++++++++++++++++++ >>>>> 4 files changed, 44 insertions(+) >>>>> >>>>> diff --git a/drivers/staging/android/ion/ion-ioctl.c >>>>> b/drivers/staging/android/ion/ion-ioctl.c >>>>> index a8d3cc4..60bb702 100644 >>>>> --- a/drivers/staging/android/ion/ion-ioctl.c >>>>> +++ b/drivers/staging/android/ion/ion-ioctl.c >>>>> @@ -12,6 +12,7 @@ >>>>> >>>>> union ion_ioctl_arg { >>>>> struct ion_allocation_data allocation; >>>>> + struct ion_buffer_flag_data update; >>>>> struct ion_heap_query query; >>>>> }; >>>>> >>>>> @@ -83,6 +84,9 @@ long ion_ioctl(struct file *filp, unsigned int >>>>> cmd, unsigned long arg) >>>>> >>>>> break; >>>>> } >>>>> + case ION_IOC_BUFFER_UPDATE: >>>>> + ret = ion_buffer_update(data.update.fd, data.update.flags); >>>>> + break; >>>>> case ION_IOC_HEAP_QUERY: >>>>> ret = ion_query_heaps(&data.query); >>>>> break; >>>>> diff --git a/drivers/staging/android/ion/ion.c >>>>> b/drivers/staging/android/ion/ion.c >>>>> index 9907332..f1404dc 100644 >>>>> --- a/drivers/staging/android/ion/ion.c >>>>> +++ b/drivers/staging/android/ion/ion.c >>>>> @@ -436,6 +436,23 @@ int ion_alloc(size_t len, unsigned int >>>> heap_id_mask, unsigned int flags) >>>>> return fd; >>>>> } >>>>> >>>>> +int ion_buffer_update(unsigned int fd, unsigned int flags) { >>>>> + struct dma_buf *dmabuf; >>>>> + struct ion_buffer *buffer; >>>>> + >>>>> + dmabuf = dma_buf_get(fd); >>>>> + >>>>> + if (!dmabuf) >>>>> + return -EINVAL; >>>>> + >>>>> + buffer = dmabuf->priv; >>>>> + buffer->flags = flags; >>>>> + dma_buf_put(dmabuf); >>>>> + >>>>> + return 0; >>>>> +} >>>>> + >>>>> int ion_query_heaps(struct ion_heap_query *query) >>>>> { >>>>> struct ion_device *dev = internal_dev; diff --git >>>>> a/drivers/staging/android/ion/ion.h >>>>> b/drivers/staging/android/ion/ion.h >>>>> index c006fc1..99bf9ab 100644 >>>>> --- a/drivers/staging/android/ion/ion.h >>>>> +++ b/drivers/staging/android/ion/ion.h >>>>> @@ -199,6 +199,7 @@ int ion_heap_pages_zero(struct page *page, >>>> size_t size, pgprot_t pgprot); >>>>> int ion_alloc(size_t len, >>>>> unsigned int heap_id_mask, >>>>> unsigned int flags); >>>>> +int ion_buffer_update(unsigned int fd, unsigned int flags); >>>>> >>>>> /** >>>>> * ion_heap_init_shrinker >>>>> diff --git a/drivers/staging/android/uapi/ion.h >>>>> b/drivers/staging/android/uapi/ion.h >>>>> index 5d70098..99753fc 100644 >>>>> --- a/drivers/staging/android/uapi/ion.h >>>>> +++ b/drivers/staging/android/uapi/ion.h >>>>> @@ -74,6 +74,20 @@ struct ion_allocation_data { >>>>> __u32 unused; >>>>> }; >>>>> >>>>> +/** >>>>> + * struct ion_buffer_flag_data - metadata passed from userspace for >>>>> +update >>>>> + * buffer flags >>>>> + * @fd: file descriptor of the buffer >>>>> + * @flags: flags passed to the buffer >>>>> + * >>>>> + * Provided by userspace as an argument to the ioctl */ >>>>> + >>>>> +struct ion_buffer_flag_data { >>>>> + __u32 fd; >>>>> + __u32 flags; >>>>> +} >>>>> + >>>>> #define MAX_HEAP_NAME 32 >>>>> >>>>> /** >>>>> @@ -116,6 +130,14 @@ struct ion_heap_query { >>>>> struct ion_allocation_data) >>>>> >>>>> /** >>>>> + * DOC: ION_IOC_BUFFER_UPDATE - update the specified ion buffer >>>> flags >>>>> + * >>>>> + * Takes an ion_buffer_flag_data structure and returns the result >>>>> +of the >>>>> + * buffer flag update operation. >>>>> + */ >>>>> +#define ION_IOC_BUFFER_UPDATE _IOWR(ION_IOC_MAGIC, 1, \ >>>>> + struct ion_buffer_flag_data) >>>>> +/** >>>>> * DOC: ION_IOC_HEAP_QUERY - information about available >> heaps >>>>> * >>>>> * Takes an ion_heap_query structure and populates information >>>> about >>>>> >>> >

6 years

Re: [Linaro-mm-sig] [PATCH] dma-buf: Change to use DEFINE_SHOW_ATTRIBUTE macro

by Daniel Vetter

On Fri, Nov 30, 2018 at 11:11:01AM -0500, Yangtao Li wrote: > Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code. > > Signed-off-by: Yangtao Li <tiny.windzz(a)gmail.com> Sorry, fell through the cracks, applied for 4.22, thanks for your patch. For next time around pls ping again after 1-2 weeks already, instead of 1-2 months. Thanks, Daniel > --- > drivers/dma-buf/dma-buf.c | 12 +----------- > drivers/dma-buf/sync_debug.c | 16 +++------------- > 2 files changed, 4 insertions(+), 24 deletions(-) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 02f7f9a89979..7c858020d14b 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -1093,17 +1093,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) > return 0; > } > > -static int dma_buf_debug_open(struct inode *inode, struct file *file) > -{ > - return single_open(file, dma_buf_debug_show, NULL); > -} > - > -static const struct file_operations dma_buf_debug_fops = { > - .open = dma_buf_debug_open, > - .read = seq_read, > - .llseek = seq_lseek, > - .release = single_release, > -}; > +DEFINE_SHOW_ATTRIBUTE(dma_buf_debug); > > static struct dentry *dma_buf_debugfs_dir; > > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c > index c4c8ecb24aa9..c0abf37df88b 100644 > --- a/drivers/dma-buf/sync_debug.c > +++ b/drivers/dma-buf/sync_debug.c > @@ -147,7 +147,7 @@ static void sync_print_sync_file(struct seq_file *s, > } > } > > -static int sync_debugfs_show(struct seq_file *s, void *unused) > +static int sync_info_debugfs_show(struct seq_file *s, void *unused) > { > struct list_head *pos; > > @@ -178,17 +178,7 @@ static int sync_debugfs_show(struct seq_file *s, void *unused) > return 0; > } > > -static int sync_info_debugfs_open(struct inode *inode, struct file *file) > -{ > - return single_open(file, sync_debugfs_show, inode->i_private); > -} > - > -static const struct file_operations sync_info_debugfs_fops = { > - .open = sync_info_debugfs_open, > - .read = seq_read, > - .llseek = seq_lseek, > - .release = single_release, > -}; > +DEFINE_SHOW_ATTRIBUTE(sync_info_debugfs); > > static __init int sync_debugfs_init(void) > { > @@ -218,7 +208,7 @@ void sync_dump(void) > }; > int i; > > - sync_debugfs_show(&s, NULL); > + sync_info_debugfs_show(&s, NULL); > > for (i = 0; i < s.count; i += DUMP_CHUNK) { > if ((s.count - i) > DUMP_CHUNK) { > -- > 2.17.0 > > _______________________________________________ > dri-devel mailing list > dri-devel(a)lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch

6 years

Re: [Linaro-mm-sig] [PATCH] staging: android: ion: add buffer flag update ioctl

by Laura Abbott

On 12/19/18 5:39 PM, Zengtao (B) wrote: > Hi laura: > >> -----Original Message----- >> From: Laura Abbott [mailto:labbott@redhat.com] >> Sent: Thursday, December 20, 2018 2:10 AM >> To: Zengtao (B) <prime.zeng(a)hisilicon.com>; sumit.semwal(a)linaro.org >> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>; Arve Hjønnevåg >> <arve(a)android.com>; Todd Kjos <tkjos(a)android.com>; Martijn Coenen >> <maco(a)android.com>; Joel Fernandes <joel(a)joelfernandes.org>; >> devel(a)driverdev.osuosl.org; dri-devel(a)lists.freedesktop.org; >> linaro-mm-sig(a)lists.linaro.org; linux-kernel(a)vger.kernel.org >> Subject: Re: [PATCH] staging: android: ion: add buffer flag update ioctl >> >> On 12/19/18 9:19 AM, Zeng Tao wrote: >>> In some usecases, the buffer cached attribute is not determined at >>> allocation time, it's determined just before the real cpu mapping. >>> And from the memory view of point, a buffer should not have the >> cached >>> attribute util is really mapped by the cpu. So in this patch, we >>> introduced the new ioctl command to target the requirement. >>> >> >> This is racy and error prone. Can you explain more what problem you are >> trying to solve? > > My use case is like this: > 1. There are two process A and B, A takes case of ion buffer allocation, and > pass the buffer fd to B, then B maps and uses it. > 2. Process B need to map the buffer with different cached attribute for > different use case, for example, if the buffer is used for pure software algorithm, > then we need to map it as cached, otherwise non-cached, and B needs to deal > with both cases. > And unfortunately the mmap syscall takes no cached flags and we can't decide > the cache attribute when we are doing the mmap, so I introduce new the ioctl > even though I think the solution is not as good. > > Thanks for the explanation, this was about the use case I expected. I'm pretty sure I had this exact problem once upon a time and we didn't come up with a solution. I'd still like to get rid of uncached buffers in general and just use cached buffers (see http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2018-Nove…) What's your usecase for uncached buffers? >> >>> Signed-off-by: Zeng Tao <prime.zeng(a)hisilicon.com> >>> --- >>> drivers/staging/android/ion/ion-ioctl.c | 4 ++++ >>> drivers/staging/android/ion/ion.c | 17 +++++++++++++++++ >>> drivers/staging/android/ion/ion.h | 1 + >>> drivers/staging/android/uapi/ion.h | 22 >> ++++++++++++++++++++++ >>> 4 files changed, 44 insertions(+) >>> >>> diff --git a/drivers/staging/android/ion/ion-ioctl.c >>> b/drivers/staging/android/ion/ion-ioctl.c >>> index a8d3cc4..60bb702 100644 >>> --- a/drivers/staging/android/ion/ion-ioctl.c >>> +++ b/drivers/staging/android/ion/ion-ioctl.c >>> @@ -12,6 +12,7 @@ >>> >>> union ion_ioctl_arg { >>> struct ion_allocation_data allocation; >>> + struct ion_buffer_flag_data update; >>> struct ion_heap_query query; >>> }; >>> >>> @@ -83,6 +84,9 @@ long ion_ioctl(struct file *filp, unsigned int cmd, >>> unsigned long arg) >>> >>> break; >>> } >>> + case ION_IOC_BUFFER_UPDATE: >>> + ret = ion_buffer_update(data.update.fd, data.update.flags); >>> + break; >>> case ION_IOC_HEAP_QUERY: >>> ret = ion_query_heaps(&data.query); >>> break; >>> diff --git a/drivers/staging/android/ion/ion.c >>> b/drivers/staging/android/ion/ion.c >>> index 9907332..f1404dc 100644 >>> --- a/drivers/staging/android/ion/ion.c >>> +++ b/drivers/staging/android/ion/ion.c >>> @@ -436,6 +436,23 @@ int ion_alloc(size_t len, unsigned int >> heap_id_mask, unsigned int flags) >>> return fd; >>> } >>> >>> +int ion_buffer_update(unsigned int fd, unsigned int flags) { >>> + struct dma_buf *dmabuf; >>> + struct ion_buffer *buffer; >>> + >>> + dmabuf = dma_buf_get(fd); >>> + >>> + if (!dmabuf) >>> + return -EINVAL; >>> + >>> + buffer = dmabuf->priv; >>> + buffer->flags = flags; >>> + dma_buf_put(dmabuf); >>> + >>> + return 0; >>> +} >>> + >>> int ion_query_heaps(struct ion_heap_query *query) >>> { >>> struct ion_device *dev = internal_dev; diff --git >>> a/drivers/staging/android/ion/ion.h >>> b/drivers/staging/android/ion/ion.h >>> index c006fc1..99bf9ab 100644 >>> --- a/drivers/staging/android/ion/ion.h >>> +++ b/drivers/staging/android/ion/ion.h >>> @@ -199,6 +199,7 @@ int ion_heap_pages_zero(struct page *page, >> size_t size, pgprot_t pgprot); >>> int ion_alloc(size_t len, >>> unsigned int heap_id_mask, >>> unsigned int flags); >>> +int ion_buffer_update(unsigned int fd, unsigned int flags); >>> >>> /** >>> * ion_heap_init_shrinker >>> diff --git a/drivers/staging/android/uapi/ion.h >>> b/drivers/staging/android/uapi/ion.h >>> index 5d70098..99753fc 100644 >>> --- a/drivers/staging/android/uapi/ion.h >>> +++ b/drivers/staging/android/uapi/ion.h >>> @@ -74,6 +74,20 @@ struct ion_allocation_data { >>> __u32 unused; >>> }; >>> >>> +/** >>> + * struct ion_buffer_flag_data - metadata passed from userspace for >>> +update >>> + * buffer flags >>> + * @fd: file descriptor of the buffer >>> + * @flags: flags passed to the buffer >>> + * >>> + * Provided by userspace as an argument to the ioctl */ >>> + >>> +struct ion_buffer_flag_data { >>> + __u32 fd; >>> + __u32 flags; >>> +} >>> + >>> #define MAX_HEAP_NAME 32 >>> >>> /** >>> @@ -116,6 +130,14 @@ struct ion_heap_query { >>> struct ion_allocation_data) >>> >>> /** >>> + * DOC: ION_IOC_BUFFER_UPDATE - update the specified ion buffer >> flags >>> + * >>> + * Takes an ion_buffer_flag_data structure and returns the result of >>> +the >>> + * buffer flag update operation. >>> + */ >>> +#define ION_IOC_BUFFER_UPDATE _IOWR(ION_IOC_MAGIC, 1, \ >>> + struct ion_buffer_flag_data) >>> +/** >>> * DOC: ION_IOC_HEAP_QUERY - information about available heaps >>> * >>> * Takes an ion_heap_query structure and populates information >> about >>> >

6 years

Re: [Linaro-mm-sig] [PATCH] staging: android: ion: add buffer flag update ioctl

by Laura Abbott

On 12/19/18 9:19 AM, Zeng Tao wrote: > In some usecases, the buffer cached attribute is not determined at > allocation time, it's determined just before the real cpu mapping. > And from the memory view of point, a buffer should not have the cached > attribute util is really mapped by the cpu. So in this patch, we > introduced the new ioctl command to target the requirement. > This is racy and error prone. Can you explain more what problem you are trying to solve? > Signed-off-by: Zeng Tao <prime.zeng(a)hisilicon.com> > --- > drivers/staging/android/ion/ion-ioctl.c | 4 ++++ > drivers/staging/android/ion/ion.c | 17 +++++++++++++++++ > drivers/staging/android/ion/ion.h | 1 + > drivers/staging/android/uapi/ion.h | 22 ++++++++++++++++++++++ > 4 files changed, 44 insertions(+) > > diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c > index a8d3cc4..60bb702 100644 > --- a/drivers/staging/android/ion/ion-ioctl.c > +++ b/drivers/staging/android/ion/ion-ioctl.c > @@ -12,6 +12,7 @@ > > union ion_ioctl_arg { > struct ion_allocation_data allocation; > + struct ion_buffer_flag_data update; > struct ion_heap_query query; > }; > > @@ -83,6 +84,9 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > break; > } > + case ION_IOC_BUFFER_UPDATE: > + ret = ion_buffer_update(data.update.fd, data.update.flags); > + break; > case ION_IOC_HEAP_QUERY: > ret = ion_query_heaps(&data.query); > break; > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c > index 9907332..f1404dc 100644 > --- a/drivers/staging/android/ion/ion.c > +++ b/drivers/staging/android/ion/ion.c > @@ -436,6 +436,23 @@ int ion_alloc(size_t len, unsigned int heap_id_mask, unsigned int flags) > return fd; > } > > +int ion_buffer_update(unsigned int fd, unsigned int flags) > +{ > + struct dma_buf *dmabuf; > + struct ion_buffer *buffer; > + > + dmabuf = dma_buf_get(fd); > + > + if (!dmabuf) > + return -EINVAL; > + > + buffer = dmabuf->priv; > + buffer->flags = flags; > + dma_buf_put(dmabuf); > + > + return 0; > +} > + > int ion_query_heaps(struct ion_heap_query *query) > { > struct ion_device *dev = internal_dev; > diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h > index c006fc1..99bf9ab 100644 > --- a/drivers/staging/android/ion/ion.h > +++ b/drivers/staging/android/ion/ion.h > @@ -199,6 +199,7 @@ int ion_heap_pages_zero(struct page *page, size_t size, pgprot_t pgprot); > int ion_alloc(size_t len, > unsigned int heap_id_mask, > unsigned int flags); > +int ion_buffer_update(unsigned int fd, unsigned int flags); > > /** > * ion_heap_init_shrinker > diff --git a/drivers/staging/android/uapi/ion.h b/drivers/staging/android/uapi/ion.h > index 5d70098..99753fc 100644 > --- a/drivers/staging/android/uapi/ion.h > +++ b/drivers/staging/android/uapi/ion.h > @@ -74,6 +74,20 @@ struct ion_allocation_data { > __u32 unused; > }; > > +/** > + * struct ion_buffer_flag_data - metadata passed from userspace for update > + * buffer flags > + * @fd: file descriptor of the buffer > + * @flags: flags passed to the buffer > + * > + * Provided by userspace as an argument to the ioctl > + */ > + > +struct ion_buffer_flag_data { > + __u32 fd; > + __u32 flags; > +} > + > #define MAX_HEAP_NAME 32 > > /** > @@ -116,6 +130,14 @@ struct ion_heap_query { > struct ion_allocation_data) > > /** > + * DOC: ION_IOC_BUFFER_UPDATE - update the specified ion buffer flags > + * > + * Takes an ion_buffer_flag_data structure and returns the result of the > + * buffer flag update operation. > + */ > +#define ION_IOC_BUFFER_UPDATE _IOWR(ION_IOC_MAGIC, 1, \ > + struct ion_buffer_flag_data) > +/** > * DOC: ION_IOC_HEAP_QUERY - information about available heaps > * > * Takes an ion_heap_query structure and populates information about >

6 years

[PATCH] dma-buf: fix debugfs versus rcu and fence dumping v2

by jglisse＠redhat.com

From: Jérôme Glisse <jglisse(a)redhat.com> The debugfs take reference on fence without dropping them. Also the rcu section are not well balance. Fix all that ... Changed since v1: - moved fobj logic around to be rcu safe Signed-off-by: Jérôme Glisse <jglisse(a)redhat.com> Cc: Christian König <christian.koenig(a)amd.com> Cc: Daniel Vetter <daniel.vetter(a)ffwll.ch> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: linux-media(a)vger.kernel.org Cc: dri-devel(a)lists.freedesktop.org Cc: linaro-mm-sig(a)lists.linaro.org Cc: Stéphane Marchesin <marcheu(a)chromium.org> Cc: stable(a)vger.kernel.org --- drivers/dma-buf/dma-buf.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 13884474d158..9688d99894d6 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1048,27 +1048,38 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) while (true) { seq = read_seqcount_begin(&robj->seq); rcu_read_lock(); - fobj = rcu_dereference(robj->fence); - shared_count = fobj ? fobj->shared_count : 0; fence = rcu_dereference(robj->fence_excl); + fence = dma_fence_get_rcu(fence); if (!read_seqcount_retry(&robj->seq, seq)) break; rcu_read_unlock(); } - - if (fence) + if (fence) { seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n", fence->ops->get_driver_name(fence), fence->ops->get_timeline_name(fence), dma_fence_is_signaled(fence) ? "" : "un"); - for (i = 0; i < shared_count; i++) { + dma_fence_put(fence); + } + + rcu_read_lock(); + fobj = rcu_dereference(robj->fence); + shared_count = fobj ? fobj->shared_count : 0; + for (i = 0, fence = NULL; i < shared_count; i++) { fence = rcu_dereference(fobj->shared[i]); if (!dma_fence_get_rcu(fence)) continue; + rcu_read_unlock(); + seq_printf(s, "\tShared fence: %s %s %ssignalled\n", fence->ops->get_driver_name(fence), fence->ops->get_timeline_name(fence), dma_fence_is_signaled(fence) ? "" : "un"); + dma_fence_put(fence); + + rcu_read_lock(); + fobj = rcu_dereference(robj->fence); + shared_count = fobj ? fobj->shared_count : 0; } rcu_read_unlock(); -- 2.17.2

6 years, 1 month

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