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Re: [PATCH v17 28/47] dept: add documentation for dept

by Bagas Sanjaya

On Thu, Oct 02, 2025 at 05:12:28PM +0900, Byungchul Park wrote: > This document describes the concept and APIs of dept. > > Signed-off-by: Byungchul Park <byungchul(a)sk.com> > --- > Documentation/dependency/dept.txt | 735 ++++++++++++++++++++++++++ > Documentation/dependency/dept_api.txt | 117 ++++ > 2 files changed, 852 insertions(+) > create mode 100644 Documentation/dependency/dept.txt > create mode 100644 Documentation/dependency/dept_api.txt What about writing dept docs in reST (like the rest of kernel documentation)? ---- >8 ---- diff --git a/Documentation/dependency/dept.txt b/Documentation/locking/dept.rst similarity index 92% rename from Documentation/dependency/dept.txt rename to Documentation/locking/dept.rst index 5dd358b96734e6..7b90a0d95f0876 100644 --- a/Documentation/dependency/dept.txt +++ b/Documentation/locking/dept.rst @@ -8,7 +8,7 @@ How lockdep works Lockdep detects a deadlock by checking lock acquisition order. For example, a graph to track acquisition order built by lockdep might look -like: +like:: A -> B - \ @@ -16,12 +16,12 @@ like: / C -> D - - where 'A -> B' means that acquisition A is prior to acquisition B - with A still held. +where 'A -> B' means that acquisition A is prior to acquisition B +with A still held. Lockdep keeps adding each new acquisition order into the graph in runtime. For example, 'E -> C' will be added when the two locks have -been acquired in the order, E and then C. The graph will look like: +been acquired in the order, E and then C. The graph will look like:: A -> B - \ @@ -32,10 +32,10 @@ been acquired in the order, E and then C. The graph will look like: \ / ------------------ - where 'A -> B' means that acquisition A is prior to acquisition B - with A still held. +where 'A -> B' means that acquisition A is prior to acquisition B +with A still held. -This graph contains a subgraph that demonstrates a loop like: +This graph contains a subgraph that demonstrates a loop like:: -> E - / \ @@ -67,6 +67,8 @@ mechanisms, lockdep doesn't work. Can lockdep detect the following deadlock? +:: + context X context Y context Z mutex_lock A @@ -80,6 +82,8 @@ Can lockdep detect the following deadlock? No. What about the following? +:: + context X context Y mutex_lock A @@ -101,7 +105,7 @@ What leads a deadlock --------------------- A deadlock occurs when one or multi contexts are waiting for events that -will never happen. For example: +will never happen. For example:: context X context Y context Z @@ -121,24 +125,24 @@ We call this *deadlock*. If an event occurrence is a prerequisite to reaching another event, we call it *dependency*. In this example: - Event A occurrence is a prerequisite to reaching event C. - Event C occurrence is a prerequisite to reaching event B. - Event B occurrence is a prerequisite to reaching event A. + * Event A occurrence is a prerequisite to reaching event C. + * Event C occurrence is a prerequisite to reaching event B. + * Event B occurrence is a prerequisite to reaching event A. In terms of dependency: - Event C depends on event A. - Event B depends on event C. - Event A depends on event B. + * Event C depends on event A. + * Event B depends on event C. + * Event A depends on event B. -Dependency graph reflecting this example will look like: +Dependency graph reflecting this example will look like:: -> C -> A -> B - / \ \ / ---------------- - where 'A -> B' means that event A depends on event B. +where 'A -> B' means that event A depends on event B. A circular dependency exists. Such a circular dependency leads a deadlock since no waiters can have desired events triggered. @@ -152,7 +156,7 @@ Introduce DEPT -------------- DEPT(DEPendency Tracker) tracks wait and event instead of lock -acquisition order so as to recognize the following situation: +acquisition order so as to recognize the following situation:: context X context Y context Z @@ -165,18 +169,18 @@ acquisition order so as to recognize the following situation: event A and builds up a dependency graph in runtime that is similar to lockdep. -The graph might look like: +The graph might look like:: -> C -> A -> B - / \ \ / ---------------- - where 'A -> B' means that event A depends on event B. +where 'A -> B' means that event A depends on event B. DEPT keeps adding each new dependency into the graph in runtime. For example, 'B -> D' will be added when event D occurrence is a -prerequisite to reaching event B like: +prerequisite to reaching event B like:: | v @@ -184,7 +188,7 @@ prerequisite to reaching event B like: . event B -After the addition, the graph will look like: +After the addition, the graph will look like:: -> D / @@ -209,6 +213,8 @@ How DEPT works Let's take a look how DEPT works with the 1st example in the section 'Limitation of lockdep'. +:: + context X context Y context Z mutex_lock A @@ -220,7 +226,7 @@ Let's take a look how DEPT works with the 1st example in the section mutex_unlock A mutex_unlock A -Adding comments to describe DEPT's view in terms of wait and event: +Adding comments to describe DEPT's view in terms of wait and event:: context X context Y context Z @@ -248,7 +254,7 @@ Adding comments to describe DEPT's view in terms of wait and event: mutex_unlock A /* event A */ -Adding more supplementary comments to describe DEPT's view in detail: +Adding more supplementary comments to describe DEPT's view in detail:: context X context Y context Z @@ -283,7 +289,7 @@ Adding more supplementary comments to describe DEPT's view in detail: mutex_unlock A /* event A that's been valid since 4 */ -Let's build up dependency graph with this example. Firstly, context X: +Let's build up dependency graph with this example. Firstly, context X:: context X @@ -292,7 +298,7 @@ Let's build up dependency graph with this example. Firstly, context X: /* start to take into account event B's context */ /* 2 */ -There are no events to create dependency. Next, context Y: +There are no events to create dependency. Next, context Y:: context Y @@ -317,13 +323,13 @@ waits between 3 and the event, event B does not create dependency. For event A, there is a wait, folio_lock B, between 1 and the event. Which means event A cannot be triggered if event B does not wake up the wait. Therefore, we can say event A depends on event B, say, 'A -> B'. The -graph will look like after adding the dependency: +graph will look like after adding the dependency:: A -> B - where 'A -> B' means that event A depends on event B. +where 'A -> B' means that event A depends on event B. -Lastly, context Z: +Lastly, context Z:: context Z @@ -343,7 +349,7 @@ wait, mutex_lock A, between 2 and the event - remind 2 is at a very start and before the wait in timeline. Which means event B cannot be triggered if event A does not wake up the wait. Therefore, we can say event B depends on event A, say, 'B -> A'. The graph will look like -after adding the dependency: +after adding the dependency:: -> A -> B - / \ @@ -367,6 +373,8 @@ Interpret DEPT report The following is the example in the section 'How DEPT works'. +:: + context X context Y context Z mutex_lock A @@ -402,7 +410,7 @@ The following is the example in the section 'How DEPT works'. We can Simplify this by replacing each waiting point with [W], each point where its event's context starts with [S] and each event with [E]. -This example will look like after the replacement: +This example will look like after the replacement:: context X context Y context Z @@ -419,6 +427,8 @@ This example will look like after the replacement: DEPT uses the symbols [W], [S] and [E] in its report as described above. The following is an example reported by DEPT for a real problem. +:: + Link: https://lore.kernel.org/lkml/6383cde5-cf4b-facf-6e07-1378a485657d@I-love.SA… Link: https://lore.kernel.org/lkml/1674268856-31807-1-git-send-email-byungchul.pa… @@ -620,6 +630,8 @@ The following is an example reported by DEPT for a real problem. Let's take a look at the summary that is the most important part. +:: + --------------------------------------------------- summary --------------------------------------------------- @@ -639,7 +651,7 @@ Let's take a look at the summary that is the most important part. [W]: the wait blocked [E]: the event not reachable -The summary shows the following scenario: +The summary shows the following scenario:: context A context B context ?(unknown) @@ -652,7 +664,7 @@ The summary shows the following scenario: [E] unlock(&ni->ni_lock:0) -Adding supplementary comments to describe DEPT's view in detail: +Adding supplementary comments to describe DEPT's view in detail:: context A context B context ?(unknown) @@ -677,7 +689,7 @@ Adding supplementary comments to describe DEPT's view in detail: [E] unlock(&ni->ni_lock:0) /* event that's been valid since 2 */ -Let's build up dependency graph with this report. Firstly, context A: +Let's build up dependency graph with this report. Firstly, context A:: context A @@ -697,13 +709,13 @@ wait, folio_lock(&f1), between 2 and the event. Which means unlock(&ni->ni_lock:0) is not reachable if folio_unlock(&f1) does not wake up the wait. Therefore, we can say unlock(&ni->ni_lock:0) depends on folio_unlock(&f1), say, 'unlock(&ni->ni_lock:0) -> folio_unlock(&f1)'. -The graph will look like after adding the dependency: +The graph will look like after adding the dependency:: unlock(&ni->ni_lock:0) -> folio_unlock(&f1) - where 'A -> B' means that event A depends on event B. +where 'A -> B' means that event A depends on event B. -Secondly, context B: +Secondly, context B:: context B @@ -719,14 +731,14 @@ very start and before the wait in timeline. Which means folio_unlock(&f1) is not reachable if unlock(&ni->ni_lock:0) does not wake up the wait. Therefore, we can say folio_unlock(&f1) depends on unlock(&ni->ni_lock:0), say, 'folio_unlock(&f1) -> unlock(&ni->ni_lock:0)'. The graph will look -like after adding the dependency: +like after adding the dependency:: -> unlock(&ni->ni_lock:0) -> folio_unlock(&f1) - / \ \ / ------------------------------------------------ - where 'A -> B' means that event A depends on event B. +where 'A -> B' means that event A depends on event B. A new loop has been created. So DEPT can report it as a deadlock! Cool! diff --git a/Documentation/dependency/dept_api.txt b/Documentation/locking/dept_api.rst similarity index 97% rename from Documentation/dependency/dept_api.txt rename to Documentation/locking/dept_api.rst index 8e0d5a118a460e..96c4d65f4a9a2d 100644 --- a/Documentation/dependency/dept_api.txt +++ b/Documentation/locking/dept_api.rst @@ -10,6 +10,8 @@ already applied into the existing synchronization primitives e.g. waitqueue, swait, wait_for_completion(), dma fence and so on. The basic APIs of SDT are: +.. code-block:: c + /* * After defining 'struct dept_map map', initialize the instance. */ @@ -27,6 +29,8 @@ APIs of SDT are: The advanced APIs of SDT are: +.. code-block:: c + /* * After defining 'struct dept_map map', initialize the instance * using an external key. @@ -83,6 +87,8 @@ Do not use these APIs directly. These are the wrappers for typical locks, that have been already applied into major locks internally e.g. spin lock, mutex, rwlock and so on. The APIs of LDT are: +.. code-block:: c + ldt_init(map, key, sub, name); ldt_lock(map, sub_local, try, nest, ip); ldt_rlock(map, sub_local, try, nest, ip, queued); @@ -96,6 +102,8 @@ Raw APIs -------- Do not use these APIs directly. The raw APIs of dept are: +.. code-block:: c + dept_free_range(start, size); dept_map_init(map, key, sub, name); dept_map_reinit(map, key, sub, name); diff --git a/Documentation/locking/index.rst b/Documentation/locking/index.rst index 6a9ea96c8bcb70..7ec3dce7fee425 100644 --- a/Documentation/locking/index.rst +++ b/Documentation/locking/index.rst @@ -24,6 +24,8 @@ Locking percpu-rw-semaphore robust-futexes robust-futex-ABI + dept + dept_api .. only:: subproject and html > +Can lockdep detect the following deadlock? > + > + context X context Y context Z > + > + mutex_lock A > + folio_lock B > + folio_lock B <- DEADLOCK > + mutex_lock A <- DEADLOCK > + folio_unlock B > + folio_unlock B > + mutex_unlock A > + mutex_unlock A > + > +No. What about the following? > + > + context X context Y > + > + mutex_lock A > + mutex_lock A <- DEADLOCK > + wait_for_complete B <- DEADLOCK > + complete B > + mutex_unlock A > + mutex_unlock A Can you explain how DEPT detects deadlock on the second example above (like the first one being described in "How DEPT works" section)? Confused... -- An old man doll... just what I always wanted! - Clara

2 months

Re: [PATCH v12 2/9] dma-buf: dma-heap: export declared functions

by John Stultz

On Thu, Oct 2, 2025 at 12:47 AM Maxime Ripard <mripard(a)redhat.com> wrote: > On Thu, Sep 11, 2025 at 03:49:43PM +0200, Jens Wiklander wrote: > > Export the dma-buf heap functions to allow them to be used by the OP-TEE > > driver. The OP-TEE driver wants to register and manage specific secure > > DMA heaps with it. > > > > Reviewed-by: Sumit Garg <sumit.garg(a)oss.qualcomm.com> > > Reviewed-by: T.J. Mercier <tjmercier(a)google.com> > > Acked-by: Sumit Semwal <sumit.semwal(a)linaro.org> > > Signed-off-by: Jens Wiklander <jens.wiklander(a)linaro.org> > > --- > > drivers/dma-buf/dma-heap.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c > > index 3cbe87d4a464..8ab49924f8b7 100644 > > --- a/drivers/dma-buf/dma-heap.c > > +++ b/drivers/dma-buf/dma-heap.c > > @@ -11,6 +11,7 @@ > > #include <linux/dma-buf.h> > > #include <linux/dma-heap.h> > > #include <linux/err.h> > > +#include <linux/export.h> > > #include <linux/list.h> > > #include <linux/nospec.h> > > #include <linux/syscalls.h> > > @@ -202,6 +203,7 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) > > { > > return heap->priv; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_get_drvdata, "DMA_BUF_HEAP"); > > > > /** > > * dma_heap_get_name - get heap name > > @@ -214,6 +216,7 @@ const char *dma_heap_get_name(struct dma_heap *heap) > > { > > return heap->name; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_get_name, "DMA_BUF_HEAP"); > > > > /** > > * dma_heap_add - adds a heap to dmabuf heaps > > @@ -303,6 +306,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) > > kfree(heap); > > return err_ret; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP"); > > It's not clear to me why we would need to export those symbols. > > As far as I know, heaps cannot be removed, and compiling them as module > means that we would be able to remove them. > > Now, if we don't expect the users to be compiled as modules, then we > don't need to export these symbols at all. > > Am I missing something? For things like distro kernels (or in Android's case, the GKI), there's a benefit for modules that can be loaded permanently (not having a module_exit hook). One doesn't have to bloat the base kernel image/memory usage for everyone, while still not having to necessarily deal with complications from module unloading issues. thanks -john

2 months

Re: [PATCH] rust: bindings: add `rust_helper_wait_for_completion` helper function

by Boqun Feng

On Thu, Oct 02, 2025 at 10:06:17AM +0000, Guangbo Cui wrote: > > -extern void wait_for_completion(struct completion *); > > -extern void wait_for_completion_io(struct completion *); > > -extern int wait_for_completion_interruptible(struct completion *x); > > -extern int wait_for_completion_killable(struct completion *x); > > -extern int wait_for_completion_state(struct completion *x, unsigned int state); > > -extern unsigned long wait_for_completion_timeout(struct completion *x, > > +extern void __wait_for_completion(struct completion *); > > +extern void __wait_for_completion_io(struct completion *); > > +extern int __wait_for_completion_interruptible(struct completion *x); > > +extern int __wait_for_completion_killable(struct completion *x); > > +extern int __wait_for_completion_state(struct completion *x, unsigned int state); > > +extern unsigned long __wait_for_completion_timeout(struct completion *x, > > unsigned long timeout); > > -extern unsigned long wait_for_completion_io_timeout(struct completion *x, > > +extern unsigned long __wait_for_completion_io_timeout(struct completion *x, > > unsigned long timeout); > > -extern long wait_for_completion_interruptible_timeout( > > +extern long __wait_for_completion_interruptible_timeout( > > struct completion *x, unsigned long timeout); > > -extern long wait_for_completion_killable_timeout( > > +extern long __wait_for_completion_killable_timeout( > > struct completion *x, unsigned long timeout); > > extern bool try_wait_for_completion(struct completion *x); > > extern bool completion_done(struct completion *x); > > @@ -139,4 +134,79 @@ extern void complete(struct completion *); > > extern void complete_on_current_cpu(struct completion *x); > > extern void complete_all(struct completion *); > > > > +#define wait_for_completion(x) \ > > +({ \ > > + sdt_might_sleep_start_timeout(NULL, -1L); \ > > + __wait_for_completion(x); \ > > + sdt_might_sleep_end(); \ > > +}) > > The DEPT patch series changed `wait_for_completion` into a macro. > Because bindgen cannot handle function-like macros, this caused > Rust build errors. Add a helper function to fix it. > > ``` > error[E0425]: cannot find function `wait_for_completion` in crate `bindings` > --> rust/kernel/sync/completion.rs:110:28 > | > 110 | unsafe { bindings::wait_for_completion(self.as_raw()) }; > | ^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `__wait_for_completion` > | > ::: /root/linux/rust/bindings/bindings_generated.rs:33440:5 > | > 33440 | pub fn __wait_for_completion(arg1: *mut completion); > | ---------------------------------------------------- similarly named function `__wait_for_completion` defined here > > error: aborting due to 1 previous error > > For more information about this error, try `rustc --explain E0425`. > ``` > I think Danilo already made it clear, please fold this the existing patch. Moreover, since this patchset doesn't adjust init_completion() from the Rust side, the result is Rust code will also use the same dept key for completion, which has to be fixed if dept wants to be in-tree. Regards, Boqun > Signed-off-by: Guangbo Cui <2407018371(a)qq.com> > --- > rust/helpers/completion.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/rust/helpers/completion.c b/rust/helpers/completion.c > index b2443262a2ae..5bae5e749def 100644 > --- a/rust/helpers/completion.c > +++ b/rust/helpers/completion.c > @@ -6,3 +6,8 @@ void rust_helper_init_completion(struct completion *x) > { > init_completion(x); > } > + > +void rust_helper_wait_for_completion(struct completion *x) > +{ > + wait_for_completion(x); > +} > -- > 2.43.0 >

2 months

Re: [PATCH v12 3/9] tee: implement protected DMA-heap

by Jens Wiklander

Hi, On Thu, Oct 2, 2025 at 9:54 AM Maxime Ripard <mripard(a)redhat.com> wrote: > > On Thu, Sep 11, 2025 at 03:49:44PM +0200, Jens Wiklander wrote: > > +static const char *heap_id_2_name(enum tee_dma_heap_id id) > > +{ > > + switch (id) { > > + case TEE_DMA_HEAP_SECURE_VIDEO_PLAY: > > + return "protected,secure-video"; > > + case TEE_DMA_HEAP_TRUSTED_UI: > > + return "protected,trusted-ui"; > > + case TEE_DMA_HEAP_SECURE_VIDEO_RECORD: > > + return "protected,secure-video-record"; > > + default: > > + return NULL; > > + } > > +} > > We've recently agreed on a naming guideline (even though it's not merged yet) > > https://lore.kernel.org/r/20250728-dma-buf-heap-names-doc-v4-1-f73f71cf0dfd… I wasn't aware of that (or had forgotten it), but during the revisions of this patch set, we changed to use "protected". > > Secure and trusted should be defined I guess, because secure and > protected at least seem redundant to me. Depending on the use case, the protected buffer is only accessible to a specific set of devices. This is typically configured by the TEE firmware based on which heap we're using. To distinguish between the different heaps, I've simply added the name of the use case after the comma. So the name of the heap for the Trusted-UI use case is "protected,trusted-ui". What would a heap called "protected,ui" represent? Protected buffers for a UI use case? What kind of UI use case? If the name of the heap is too generic, it might cover more than one use case with conflicting requirements for which devices should be able to access the protected memory. Thanks, Jens

2 months

Re: [PATCH v12 2/9] dma-buf: dma-heap: export declared functions

by Nicolas Dufresne

Le jeudi 02 octobre 2025 à 09:47 +0200, Maxime Ripard a écrit : > Hi, > > On Thu, Sep 11, 2025 at 03:49:43PM +0200, Jens Wiklander wrote: > > Export the dma-buf heap functions to allow them to be used by the OP-TEE > > driver. The OP-TEE driver wants to register and manage specific secure > > DMA heaps with it. > > > > Reviewed-by: Sumit Garg <sumit.garg(a)oss.qualcomm.com> > > Reviewed-by: T.J. Mercier <tjmercier(a)google.com> > > Acked-by: Sumit Semwal <sumit.semwal(a)linaro.org> > > Signed-off-by: Jens Wiklander <jens.wiklander(a)linaro.org> > > --- > > drivers/dma-buf/dma-heap.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c > > index 3cbe87d4a464..8ab49924f8b7 100644 > > --- a/drivers/dma-buf/dma-heap.c > > +++ b/drivers/dma-buf/dma-heap.c > > @@ -11,6 +11,7 @@ > > #include <linux/dma-buf.h> > > #include <linux/dma-heap.h> > > #include <linux/err.h> > > +#include <linux/export.h> > > #include <linux/list.h> > > #include <linux/nospec.h> > > #include <linux/syscalls.h> > > @@ -202,6 +203,7 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) > > { > > return heap->priv; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_get_drvdata, "DMA_BUF_HEAP"); > > > > /** > > * dma_heap_get_name - get heap name > > @@ -214,6 +216,7 @@ const char *dma_heap_get_name(struct dma_heap *heap) > > { > > return heap->name; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_get_name, "DMA_BUF_HEAP"); > > > > /** > > * dma_heap_add - adds a heap to dmabuf heaps > > @@ -303,6 +306,7 @@ struct dma_heap *dma_heap_add(const struct > > dma_heap_export_info *exp_info) > > kfree(heap); > > return err_ret; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP"); > > It's not clear to me why we would need to export those symbols. > > As far as I know, heaps cannot be removed, and compiling them as module > means that we would be able to remove them. > > Now, if we don't expect the users to be compiled as modules, then we > don't need to export these symbols at all. Maybe I'm getting out of topic, sorry if its the case, but making that a hard rule seems very limiting. Didn't we said that a heap driver could be made to represent memory region on a remote device such as an eGPU ? Nicolas > > Am I missing something? > > Maxime

2 months

Re: [PATCH v12 2/9] dma-buf: dma-heap: export declared functions

by Jens Wiklander

Hi, On Thu, Oct 2, 2025 at 9:47 AM Maxime Ripard <mripard(a)redhat.com> wrote: > > Hi, > > On Thu, Sep 11, 2025 at 03:49:43PM +0200, Jens Wiklander wrote: > > Export the dma-buf heap functions to allow them to be used by the OP-TEE > > driver. The OP-TEE driver wants to register and manage specific secure > > DMA heaps with it. > > > > Reviewed-by: Sumit Garg <sumit.garg(a)oss.qualcomm.com> > > Reviewed-by: T.J. Mercier <tjmercier(a)google.com> > > Acked-by: Sumit Semwal <sumit.semwal(a)linaro.org> > > Signed-off-by: Jens Wiklander <jens.wiklander(a)linaro.org> > > --- > > drivers/dma-buf/dma-heap.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c > > index 3cbe87d4a464..8ab49924f8b7 100644 > > --- a/drivers/dma-buf/dma-heap.c > > +++ b/drivers/dma-buf/dma-heap.c > > @@ -11,6 +11,7 @@ > > #include <linux/dma-buf.h> > > #include <linux/dma-heap.h> > > #include <linux/err.h> > > +#include <linux/export.h> > > #include <linux/list.h> > > #include <linux/nospec.h> > > #include <linux/syscalls.h> > > @@ -202,6 +203,7 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) > > { > > return heap->priv; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_get_drvdata, "DMA_BUF_HEAP"); > > > > /** > > * dma_heap_get_name - get heap name > > @@ -214,6 +216,7 @@ const char *dma_heap_get_name(struct dma_heap *heap) > > { > > return heap->name; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_get_name, "DMA_BUF_HEAP"); > > > > /** > > * dma_heap_add - adds a heap to dmabuf heaps > > @@ -303,6 +306,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) > > kfree(heap); > > return err_ret; > > } > > +EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP"); > > It's not clear to me why we would need to export those symbols. > > As far as I know, heaps cannot be removed, and compiling them as module > means that we would be able to remove them. > > Now, if we don't expect the users to be compiled as modules, then we > don't need to export these symbols at all. > > Am I missing something? In this case, it's the TEE module that _might_ need to instantiate a DMA heap. Whether it will be instantiated depends on the TEE backend driver and the TEE firmware. If a heap is instantiated, then it will not be possible to unload the TEE module. That might not be perfect, but in my opinion, it's better than other options, such as always making the TEE subsystem built-in or disabling DMA-heap support when compiled as a module. Thanks, Jens

2 months

Re: [PATCH v17 09/47] arm64, dept: add support CONFIG_ARCH_HAS_DEPT_SUPPORT to arm64

by Mark Brown

On Thu, Oct 02, 2025 at 05:12:09PM +0900, Byungchul Park wrote: > dept needs to notice every entrance from user to kernel mode to treat > every kernel context independently when tracking wait-event dependencies. > Roughly, system call and user oriented fault are the cases. > > Make dept aware of the entrances of arm64 and add support > CONFIG_ARCH_HAS_DEPT_SUPPORT to arm64. The description of what needs to be tracked probably needs some tightening up here, it's not clear to me for example why exceptions for mops or the vector extensions aren't included here, or what the distinction is with error faults like BTI or GCS not being tracked?

2 months

Re: [PATCH] rust: bindings: add `rust_helper_wait_for_completion` helper function

by Miguel Ojeda

On Thu, Oct 2, 2025 at 12:12 PM Guangbo Cui <2407018371(a)qq.com> wrote: > > The DEPT patch series changed `wait_for_completion` into a macro. Thanks! In general, it is useful to provide a Link: to Lore to the right patch (i.e. context is good), and please clarify in which tree you found the issue if any -- I don't see it in linux-next, so I imagine it is not applied, but "changed" sounds like it was? If it was actually applied, please also provide a Fixes: tag. Cheers, Miguel

2 months

[PATCH v4 00/10] vfio/pci: Allow MMIO regions to be exported through dma-buf

by Leon Romanovsky

Changelog: v4: * Split pcim_p2pdma_provider() to two functions, one that initializes array of providers and another to return right provider pointer. v3: https://lore.kernel.org/all/cover.1758804980.git.leon@kernel.org * Changed pcim_p2pdma_enable() to be pcim_p2pdma_provider(). * Cache provider in vfio_pci_dma_buf struct instead of BAR index. * Removed misleading comment from pcim_p2pdma_provider(). * Moved MMIO check to be in pcim_p2pdma_provider(). v2: https://lore.kernel.org/all/cover.1757589589.git.leon@kernel.org/ * Added extra patch which adds new CONFIG, so next patches can reuse it. * Squashed "PCI/P2PDMA: Remove redundant bus_offset from map state" into the other patch. * Fixed revoke calls to be aligned with true->false semantics. * Extended p2pdma_providers to be per-BAR and not global to whole device. * Fixed possible race between dmabuf states and revoke. * Moved revoke to PCI BAR zap block. v1: https://lore.kernel.org/all/cover.1754311439.git.leon@kernel.org * Changed commit messages. * Reused DMA_ATTR_MMIO attribute. * Returned support for multiple DMA ranges per-dMABUF. v0: https://lore.kernel.org/all/cover.1753274085.git.leonro@nvidia.com --------------------------------------------------------------------------- Based on "[PATCH v6 00/16] dma-mapping: migrate to physical address-based API" https://lore.kernel.org/all/cover.1757423202.git.leonro@nvidia.com/ series. --------------------------------------------------------------------------- This series extends the VFIO PCI subsystem to support exporting MMIO regions from PCI device BARs as dma-buf objects, enabling safe sharing of non-struct page memory with controlled lifetime management. This allows RDMA and other subsystems to import dma-buf FDs and build them into memory regions for PCI P2P operations. The series supports a use case for SPDK where a NVMe device will be owned by SPDK through VFIO but interacting with a RDMA device. The RDMA device may directly access the NVMe CMB or directly manipulate the NVMe device's doorbell using PCI P2P. However, as a general mechanism, it can support many other scenarios with VFIO. This dmabuf approach can be usable by iommufd as well for generic and safe P2P mappings. In addition to the SPDK use-case mentioned above, the capability added in this patch series can also be useful when a buffer (located in device memory such as VRAM) needs to be shared between any two dGPU devices or instances (assuming one of them is bound to VFIO PCI) as long as they are P2P DMA compatible. The implementation provides a revocable attachment mechanism using dma-buf move operations. MMIO regions are normally pinned as BARs don't change physical addresses, but access is revoked when the VFIO device is closed or a PCI reset is issued. This ensures kernel self-defense against potentially hostile userspace. The series includes significant refactoring of the PCI P2PDMA subsystem to separate core P2P functionality from memory allocation features, making it more modular and suitable for VFIO use cases that don't need struct page support. ----------------------------------------------------------------------- The series is based originally on https://lore.kernel.org/all/20250307052248.405803-1-vivek.kasireddy@intel.c… but heavily rewritten to be based on DMA physical API. ----------------------------------------------------------------------- The WIP branch can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?h=… Thanks Leon Romanovsky (8): PCI/P2PDMA: Separate the mmap() support from the core logic PCI/P2PDMA: Simplify bus address mapping API PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation PCI/P2PDMA: Export pci_p2pdma_map_type() function types: move phys_vec definition to common header vfio/pci: Add dma-buf export config for MMIO regions vfio/pci: Enable peer-to-peer DMA transactions by default vfio/pci: Add dma-buf export support for MMIO regions Vivek Kasireddy (2): vfio: Export vfio device get and put registration helpers vfio/pci: Share the core device pointer while invoking feature functions block/blk-mq-dma.c | 7 +- drivers/iommu/dma-iommu.c | 4 +- drivers/pci/p2pdma.c | 177 +++++++++---- drivers/vfio/pci/Kconfig | 20 ++ drivers/vfio/pci/Makefile | 2 + drivers/vfio/pci/vfio_pci_config.c | 22 +- drivers/vfio/pci/vfio_pci_core.c | 56 ++-- drivers/vfio/pci/vfio_pci_dmabuf.c | 398 +++++++++++++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 23 ++ drivers/vfio/vfio_main.c | 2 + include/linux/pci-p2pdma.h | 120 +++++---- include/linux/types.h | 5 + include/linux/vfio.h | 2 + include/linux/vfio_pci_core.h | 3 + include/uapi/linux/vfio.h | 25 ++ kernel/dma/direct.c | 4 +- mm/hmm.c | 2 +- 17 files changed, 750 insertions(+), 122 deletions(-) create mode 100644 drivers/vfio/pci/vfio_pci_dmabuf.c -- 2.51.0

2 months, 1 week

Re: [PATCH 08/29] media: mfc: Add Exynos‑MFC driver probe support

by Krzysztof Kozlowski

On Tue, 30 Sept 2025 at 12:56, Himanshu Dewangan <h.dewangan(a)samsung.com> wrote: > > From: Nagaraju Siddineni <nagaraju.s(a)samsung.com> > > Introduce a new Kconfig entry VIDEO_EXYNOS_MFC for the Samsung > Exynos MFC driver that supports firmware version 13 and later. > Extend the top‑level Samsung platform Kconfig to disable the legacy > S5P‑MFC driver when its firmware version is > v12 and to select the > new Exynos‑MFC driver only when VIDEO_SAMSUNG_S5P_MFC is not enabled. > > Add exynos-mfc Kconfig and Makefile for probe functionality and creation > of decoder and encoder device files by registering the driver object > exynos_mfc.o and other relevant source files. > > Provide header files mfc_core_ops.h and mfc_rm.h containing core > operation prototypes, resource‑manager helpers, > and core‑selection utilities. > > Add a configurable option MFC_USE_COREDUMP to enable core‑dump > support for debugging MFC errors. > > These changes bring support for newer Exynos‑based MFC hardware, > cleanly separate it from the legacy S5P‑MFC driver, and lay the > groundwork for future feature development and debugging. > No, NAK. Existing driver is well tested and already used on newest Exynos SoC, so all this new driver is exactly how you should not work in upstream. You need to integrate into existing driver. Samsung received this review multiple times already. Best regards, Krzysztof

2 months, 1 week

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