When hcd->localmem_pool is non-null, it is used to allocate DMA memory. In this case, the dma address will be properly returned (in dma_handle), and dma_mmap_coherent should be used to map this memory into the user space. However, the current implementation uses pfn_remap_range, which is supposed to map normal pages (instead of DMA pages).
Instead of repeating the logic in the memory allocation function, this patch introduces a more robust solution. To address the previous issue, this patch checks the type of allocated memory by testing whether dma_handle is properly set. If dma_handle is properly returned, it means some DMA pages are allocated and dma_mmap_coherent should be used to map them. Otherwise, normal pages are allocated and pfn_remap_range should be called. This ensures that the correct mmap functions are used consistently, independently with logic details that determine which type of memory gets allocated.
Fixes: a0e710a7def4 ("USB: usbfs: fix mmap dma mismatch") Cc: stable@vger.kernel.org Signed-off-by: Ruihan Li lrh2000@pku.edu.cn --- drivers/usb/core/devio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index b4cf9e860..5067030b7 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -235,7 +235,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) size_t size = vma->vm_end - vma->vm_start; void *mem; unsigned long flags; - dma_addr_t dma_handle; + dma_addr_t dma_handle = DMA_MAPPING_ERROR; int ret;
ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory)); @@ -265,7 +265,13 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) usbm->vma_use_count = 1; INIT_LIST_HEAD(&usbm->memlist);
- if (hcd->localmem_pool || !hcd_uses_dma(hcd)) { + /* In DMA-unavailable cases, hcd_buffer_alloc_pages allocates + * normal pages and assigns DMA_MAPPING_ERROR to dma_handle. Check + * whether we are in such cases, and then use remap_pfn_range (or + * dma_mmap_coherent) to map normal (or DMA) pages into the user + * space, respectively. + */ + if (dma_handle == DMA_MAPPING_ERROR) { if (remap_pfn_range(vma, vma->vm_start, virt_to_phys(usbm->mem) >> PAGE_SHIFT, size, vma->vm_page_prot) < 0) {
On Wed, May 10, 2023 at 04:55:25PM +0800, Ruihan Li wrote:
When hcd->localmem_pool is non-null, it is used to allocate DMA memory. In this case, the dma address will be properly returned (in dma_handle), and dma_mmap_coherent should be used to map this memory into the user space. However, the current implementation uses pfn_remap_range, which is supposed to map normal pages (instead of DMA pages).
Instead of repeating the logic in the memory allocation function, this patch introduces a more robust solution. To address the previous issue, this patch checks the type of allocated memory by testing whether dma_handle is properly set. If dma_handle is properly returned, it means some DMA pages are allocated and dma_mmap_coherent should be used to map them. Otherwise, normal pages are allocated and pfn_remap_range should be called. This ensures that the correct mmap functions are used consistently, independently with logic details that determine which type of memory gets allocated.
Fixes: a0e710a7def4 ("USB: usbfs: fix mmap dma mismatch") Cc: stable@vger.kernel.org Signed-off-by: Ruihan Li lrh2000@pku.edu.cn
drivers/usb/core/devio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index b4cf9e860..5067030b7 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -235,7 +235,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) size_t size = vma->vm_end - vma->vm_start; void *mem; unsigned long flags;
- dma_addr_t dma_handle;
- dma_addr_t dma_handle = DMA_MAPPING_ERROR; int ret;
ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory)); @@ -265,7 +265,13 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) usbm->vma_use_count = 1; INIT_LIST_HEAD(&usbm->memlist);
- if (hcd->localmem_pool || !hcd_uses_dma(hcd)) {
- /* In DMA-unavailable cases, hcd_buffer_alloc_pages allocates
* normal pages and assigns DMA_MAPPING_ERROR to dma_handle. Check* whether we are in such cases, and then use remap_pfn_range (or* dma_mmap_coherent) to map normal (or DMA) pages into the user* space, respectively.*/
Another stylistic issue. For multi-line comments, the format we use is:
/* * Blah, blah, blah * Blah, blah, blah */
Alan Stern
Hi Alan,
On Wed, May 10, 2023 at 10:38:48AM -0400, Alan Stern wrote:
On Wed, May 10, 2023 at 04:55:25PM +0800, Ruihan Li wrote:
When hcd->localmem_pool is non-null, it is used to allocate DMA memory. In this case, the dma address will be properly returned (in dma_handle), and dma_mmap_coherent should be used to map this memory into the user space. However, the current implementation uses pfn_remap_range, which is supposed to map normal pages (instead of DMA pages).
Instead of repeating the logic in the memory allocation function, this patch introduces a more robust solution. To address the previous issue, this patch checks the type of allocated memory by testing whether dma_handle is properly set. If dma_handle is properly returned, it means some DMA pages are allocated and dma_mmap_coherent should be used to map them. Otherwise, normal pages are allocated and pfn_remap_range should be called. This ensures that the correct mmap functions are used consistently, independently with logic details that determine which type of memory gets allocated.
Fixes: a0e710a7def4 ("USB: usbfs: fix mmap dma mismatch") Cc: stable@vger.kernel.org Signed-off-by: Ruihan Li lrh2000@pku.edu.cn
drivers/usb/core/devio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index b4cf9e860..5067030b7 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -235,7 +235,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) size_t size = vma->vm_end - vma->vm_start; void *mem; unsigned long flags;
- dma_addr_t dma_handle;
- dma_addr_t dma_handle = DMA_MAPPING_ERROR; int ret;
ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory)); @@ -265,7 +265,13 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) usbm->vma_use_count = 1; INIT_LIST_HEAD(&usbm->memlist);
- if (hcd->localmem_pool || !hcd_uses_dma(hcd)) {
- /* In DMA-unavailable cases, hcd_buffer_alloc_pages allocates
* normal pages and assigns DMA_MAPPING_ERROR to dma_handle. Check* whether we are in such cases, and then use remap_pfn_range (or* dma_mmap_coherent) to map normal (or DMA) pages into the user* space, respectively.*/Another stylistic issue. For multi-line comments, the format we use is:
/* * Blah, blah, blah * Blah, blah, blah */
Alan Stern
Yeah, I am pretty sure it is another style difference with the net subsystem. Again, in the next version, I'll follow the coding style that you have pointed out.
Thanks, Ruihan Li
On 10.05.23 17:41, Ruihan Li wrote:
Hi Alan,
On Wed, May 10, 2023 at 10:38:48AM -0400, Alan Stern wrote:
On Wed, May 10, 2023 at 04:55:25PM +0800, Ruihan Li wrote:
When hcd->localmem_pool is non-null, it is used to allocate DMA memory. In this case, the dma address will be properly returned (in dma_handle), and dma_mmap_coherent should be used to map this memory into the user space. However, the current implementation uses pfn_remap_range, which is supposed to map normal pages (instead of DMA pages).
Instead of repeating the logic in the memory allocation function, this patch introduces a more robust solution. To address the previous issue, this patch checks the type of allocated memory by testing whether dma_handle is properly set. If dma_handle is properly returned, it means some DMA pages are allocated and dma_mmap_coherent should be used to map them. Otherwise, normal pages are allocated and pfn_remap_range should be called. This ensures that the correct mmap functions are used consistently, independently with logic details that determine which type of memory gets allocated.
Fixes: a0e710a7def4 ("USB: usbfs: fix mmap dma mismatch") Cc: stable@vger.kernel.org Signed-off-by: Ruihan Li lrh2000@pku.edu.cn
drivers/usb/core/devio.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index b4cf9e860..5067030b7 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -235,7 +235,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) size_t size = vma->vm_end - vma->vm_start; void *mem; unsigned long flags;
- dma_addr_t dma_handle;
- dma_addr_t dma_handle = DMA_MAPPING_ERROR; int ret;
ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory)); @@ -265,7 +265,13 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) usbm->vma_use_count = 1; INIT_LIST_HEAD(&usbm->memlist);
- if (hcd->localmem_pool || !hcd_uses_dma(hcd)) {
- /* In DMA-unavailable cases, hcd_buffer_alloc_pages allocates
* normal pages and assigns DMA_MAPPING_ERROR to dma_handle. Check* whether we are in such cases, and then use remap_pfn_range (or* dma_mmap_coherent) to map normal (or DMA) pages into the user* space, respectively.*/Another stylistic issue. For multi-line comments, the format we use is:
/* * Blah, blah, blah * Blah, blah, blah */
Alan Stern
Yeah, I am pretty sure it is another style difference with the net subsystem. Again, in the next version, I'll follow the coding style that you have pointed out.
Documentation/process/coding-style.rst
spells out that net/ and drivers/net/ are "special".
Regarding breaking long lines, it's just an inconsistent, undocumented mess IIRC ...
linux-stable-mirror@lists.linaro.org
-
Alan Stern -
David Hildenbrand -
Ruihan Li