From 122020af856181c24fe45903e43e3cc987c175f7 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 15 Nov 2016 15:46:42 +0000 Subject: dma-buf: Provide wrappers for reservation's lock Joonas complained that writing ww_mutex_lock(&resv->lock, ctx) was too intrusive compared to reservation_object_lock(resv, ctx); Signed-off-by: Chris Wilson Cc: Sumit Semwal Cc: Joonas Lahtinen Reviewed-by: Alex Deucher Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161115154642.31850-1-chris@chris-wilson.co.uk --- include/linux/reservation.h | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'include/linux') diff --git a/include/linux/reservation.h b/include/linux/reservation.h index d9706a6f5ae2..2b5a4679daea 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -144,6 +144,40 @@ reservation_object_get_list(struct reservation_object *obj) reservation_object_held(obj)); } +/** + * reservation_object_lock - lock the reservation object + * @obj: the reservation object + * @ctx: the locking context + * + * Locks the reservation object for exclusive access and modification. Note, + * that the lock is only against other writers, readers will run concurrently + * with a writer under RCU. The seqlock is used to notify readers if they + * overlap with a writer. + * + * As the reservation object may be locked by multiple parties in an + * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle + * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation + * object may be locked by itself by passing NULL as @ctx. + */ +static inline int +reservation_object_lock(struct reservation_object *obj, + struct ww_acquire_ctx *ctx) +{ + return ww_mutex_lock(&obj->lock, ctx); +} + +/** + * reservation_object_unlock - unlock the reservation object + * @obj: the reservation object + * + * Unlocks the reservation object following exclusive access. + */ +static inline void +reservation_object_unlock(struct reservation_object *obj) +{ + ww_mutex_unlock(&obj->lock); +} + /** * reservation_object_get_excl - get the reservation object's * exclusive fence, with update-side lock held -- cgit v1.2.3 From 2904a8c1311f02896635fd35744262413a0b2726 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 9 Dec 2016 19:53:07 +0100 Subject: dma-buf: Reorganize device dma access docs - Put the initial overview for dma-buf into dma-buf.rst. - Put all the comments about detailed semantics into the right kernel-doc comment for functions or ops structure member. - To allow that detail, switch the reworked kerneldoc to inline style for dma_buf_ops. - Tie everything together into a much more streamlined overview comment, relying on the hyperlinks for all the details. - Also sprinkle some links into the kerneldoc for dma_buf and dma_buf_attachment to tie it all together. Cc: linux-doc@vger.kernel.org Cc: Jonathan Corbet Cc: Sumit Semwal Signed-off-by: Daniel Vetter Signed-off-by: Sumit Semwal Link: http://patchwork.freedesktop.org/patch/msgid/20161209185309.1682-4-daniel.vetter@ffwll.ch --- include/linux/dma-buf.h | 133 +++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 110 insertions(+), 23 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 8daeb3ce0016..6df170fb243f 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -39,19 +39,6 @@ struct dma_buf_attachment; /** * struct dma_buf_ops - operations possible on struct dma_buf - * @attach: [optional] allows different devices to 'attach' themselves to the - * given buffer. It might return -EBUSY to signal that backing storage - * is already allocated and incompatible with the requirements - * of requesting device. - * @detach: [optional] detach a given device from this buffer. - * @map_dma_buf: returns list of scatter pages allocated, increases usecount - * of the buffer. Requires atleast one attach to be called - * before. Returned sg list should already be mapped into - * _device_ address space. This call may sleep. May also return - * -EINTR. Should return -EINVAL if attach hasn't been called yet. - * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter - * pages. - * @release: release this buffer; to be called after the last dma_buf_put. * @begin_cpu_access: [optional] called before cpu access to invalidate cpu * caches and allocate backing storage (if not yet done) * respectively pin the object into memory. @@ -72,25 +59,109 @@ struct dma_buf_attachment; * @vunmap: [optional] unmaps a vmap from the buffer */ struct dma_buf_ops { + /** + * @attach: + * + * This is called from dma_buf_attach() to make sure that a given + * &device can access the provided &dma_buf. Exporters which support + * buffer objects in special locations like VRAM or device-specific + * carveout areas should check whether the buffer could be move to + * system memory (or directly accessed by the provided device), and + * otherwise need to fail the attach operation. + * + * The exporter should also in general check whether the current + * allocation fullfills the DMA constraints of the new device. If this + * is not the case, and the allocation cannot be moved, it should also + * fail the attach operation. + * + * Any exporter-private housekeeping data can be stored in the priv + * pointer of &dma_buf_attachment structure. + * + * This callback is optional. + * + * Returns: + * + * 0 on success, negative error code on failure. It might return -EBUSY + * to signal that backing storage is already allocated and incompatible + * with the requirements of requesting device. + */ int (*attach)(struct dma_buf *, struct device *, - struct dma_buf_attachment *); + struct dma_buf_attachment *); + /** + * @detach: + * + * This is called by dma_buf_detach() to release a &dma_buf_attachment. + * Provided so that exporters can clean up any housekeeping for an + * &dma_buf_attachment. + * + * This callback is optional. + */ void (*detach)(struct dma_buf *, struct dma_buf_attachment *); - /* For {map,unmap}_dma_buf below, any specific buffer attributes - * required should get added to device_dma_parameters accessible - * via dev->dma_params. + /** + * @map_dma_buf: + * + * This is called by dma_buf_map_attachment() and is used to map a + * shared &dma_buf into device address space, and it is mandatory. It + * can only be called if @attach has been called successfully. This + * essentially pins the DMA buffer into place, and it cannot be moved + * any more + * + * This call may sleep, e.g. when the backing storage first needs to be + * allocated, or moved to a location suitable for all currently attached + * devices. + * + * Note that any specific buffer attributes required for this function + * should get added to device_dma_parameters accessible via + * device->dma_params from the &dma_buf_attachment. The @attach callback + * should also check these constraints. + * + * If this is being called for the first time, the exporter can now + * choose to scan through the list of attachments for this buffer, + * collate the requirements of the attached devices, and choose an + * appropriate backing storage for the buffer. + * + * Based on enum dma_data_direction, it might be possible to have + * multiple users accessing at the same time (for reading, maybe), or + * any other kind of sharing that the exporter might wish to make + * available to buffer-users. + * + * Returns: + * + * A &sg_table scatter list of or the backing storage of the DMA buffer, + * already mapped into the device address space of the &device attached + * with the provided &dma_buf_attachment. + * + * On failure, returns a negative error value wrapped into a pointer. + * May also return -EINTR when a signal was received while being + * blocked. */ struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *, - enum dma_data_direction); + enum dma_data_direction); + /** + * @unmap_dma_buf: + * + * This is called by dma_buf_unmap_attachment() and should unmap and + * release the &sg_table allocated in @map_dma_buf, and it is mandatory. + * It should also unpin the backing storage if this is the last mapping + * of the DMA buffer, it the exporter supports backing storage + * migration. + */ void (*unmap_dma_buf)(struct dma_buf_attachment *, - struct sg_table *, - enum dma_data_direction); + struct sg_table *, + enum dma_data_direction); + /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY * if the call would block. */ - /* after final dma_buf_put() */ + /** + * @release: + * + * Called after the last dma_buf_put to release the &dma_buf, and + * mandatory. + */ void (*release)(struct dma_buf *); int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction); @@ -124,6 +195,15 @@ struct dma_buf_ops { * @poll: for userspace poll support * @cb_excl: for userspace poll support * @cb_shared: for userspace poll support + * + * This represents a shared buffer, created by calling dma_buf_export(). The + * userspace representation is a normal file descriptor, which can be created by + * calling dma_buf_fd(). + * + * Shared dma buffers are reference counted using dma_buf_put() and + * get_dma_buf(). + * + * Device DMA access is handled by the separate struct &dma_buf_attachment. */ struct dma_buf { size_t size; @@ -160,6 +240,11 @@ struct dma_buf { * This structure holds the attachment information between the dma_buf buffer * and its user device(s). The list contains one attachment struct per device * attached to the buffer. + * + * An attachment is created by calling dma_buf_attach(), and released again by + * calling dma_buf_detach(). The DMA mapping itself needed to initiate a + * transfer is created by dma_buf_map_attachment() and freed again by calling + * dma_buf_unmap_attachment(). */ struct dma_buf_attachment { struct dma_buf *dmabuf; @@ -192,9 +277,11 @@ struct dma_buf_export_info { }; /** - * helper macro for exporters; zeros and fills in most common values - * + * DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters * @name: export-info name + * + * DEFINE_DMA_BUF_EXPORT_INFO macro defines the struct &dma_buf_export_info, + * zeroes it out and pre-populates exp_name in it. */ #define DEFINE_DMA_BUF_EXPORT_INFO(name) \ struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \ -- cgit v1.2.3 From 0959a1683d78270bab6381d498707fb8655ae11c Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 9 Dec 2016 19:53:08 +0100 Subject: dma-buf: Update cpu access documentation - Again move the information relevant for driver writers next to the callbacks. - Put the overview and userspace interface documentation into a DOC: section within the code. - Remove the text that mmap needs to be coherent - since the DMA_BUF_IOCTL_SYNC landed that's no longer the case. But keep the text that for pte zapping exporters need to adjust the address space. - Add a FIXME that kmap and the new begin/end stuff used by the SYNC ioctl don't really mix correctly. That's something I just realized while doing this doc rework. - Augment function and structure docs like usual. Cc: linux-doc@vger.kernel.org Cc: Jonathan Corbet Cc: Sumit Semwal Signed-off-by: Daniel Vetter Signed-off-by: Sumit Semwal [sumits: fix cosmetic issues] Link: http://patchwork.freedesktop.org/patch/msgid/20161209185309.1682-5-daniel.vetter@ffwll.ch --- include/linux/dma-buf.h | 91 ++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 83 insertions(+), 8 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 6df170fb243f..57828154e440 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -39,10 +39,6 @@ struct dma_buf_attachment; /** * struct dma_buf_ops - operations possible on struct dma_buf - * @begin_cpu_access: [optional] called before cpu access to invalidate cpu - * caches and allocate backing storage (if not yet done) - * respectively pin the object into memory. - * @end_cpu_access: [optional] called after cpu access to flush caches. * @kmap_atomic: maps a page from the buffer into kernel address * space, users may not block until the subsequent unmap call. * This callback must not sleep. @@ -50,10 +46,6 @@ struct dma_buf_attachment; * This Callback must not sleep. * @kmap: maps a page from the buffer into kernel address space. * @kunmap: [optional] unmaps a page from the buffer. - * @mmap: used to expose the backing storage to userspace. Note that the - * mapping needs to be coherent - if the exporter doesn't directly - * support this, it needs to fake coherency by shooting down any ptes - * when transitioning away from the cpu domain. * @vmap: [optional] creates a virtual mapping for the buffer into kernel * address space. Same restrictions as for vmap and friends apply. * @vunmap: [optional] unmaps a vmap from the buffer @@ -164,13 +156,96 @@ struct dma_buf_ops { */ void (*release)(struct dma_buf *); + /** + * @begin_cpu_access: + * + * This is called from dma_buf_begin_cpu_access() and allows the + * exporter to ensure that the memory is actually available for cpu + * access - the exporter might need to allocate or swap-in and pin the + * backing storage. The exporter also needs to ensure that cpu access is + * coherent for the access direction. The direction can be used by the + * exporter to optimize the cache flushing, i.e. access with a different + * direction (read instead of write) might return stale or even bogus + * data (e.g. when the exporter needs to copy the data to temporary + * storage). + * + * This callback is optional. + * + * FIXME: This is both called through the DMA_BUF_IOCTL_SYNC command + * from userspace (where storage shouldn't be pinned to avoid handing + * de-factor mlock rights to userspace) and for the kernel-internal + * users of the various kmap interfaces, where the backing storage must + * be pinned to guarantee that the atomic kmap calls can succeed. Since + * there's no in-kernel users of the kmap interfaces yet this isn't a + * real problem. + * + * Returns: + * + * 0 on success or a negative error code on failure. This can for + * example fail when the backing storage can't be allocated. Can also + * return -ERESTARTSYS or -EINTR when the call has been interrupted and + * needs to be restarted. + */ int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction); + + /** + * @end_cpu_access: + * + * This is called from dma_buf_end_cpu_access() when the importer is + * done accessing the CPU. The exporter can use this to flush caches and + * unpin any resources pinned in @begin_cpu_access. + * The result of any dma_buf kmap calls after end_cpu_access is + * undefined. + * + * This callback is optional. + * + * Returns: + * + * 0 on success or a negative error code on failure. Can return + * -ERESTARTSYS or -EINTR when the call has been interrupted and needs + * to be restarted. + */ int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction); void *(*kmap_atomic)(struct dma_buf *, unsigned long); void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *); void *(*kmap)(struct dma_buf *, unsigned long); void (*kunmap)(struct dma_buf *, unsigned long, void *); + /** + * @mmap: + * + * This callback is used by the dma_buf_mmap() function + * + * Note that the mapping needs to be incoherent, userspace is expected + * to braket CPU access using the DMA_BUF_IOCTL_SYNC interface. + * + * Because dma-buf buffers have invariant size over their lifetime, the + * dma-buf core checks whether a vma is too large and rejects such + * mappings. The exporter hence does not need to duplicate this check. + * Drivers do not need to check this themselves. + * + * If an exporter needs to manually flush caches and hence needs to fake + * coherency for mmap support, it needs to be able to zap all the ptes + * pointing at the backing storage. Now linux mm needs a struct + * address_space associated with the struct file stored in vma->vm_file + * to do that with the function unmap_mapping_range. But the dma_buf + * framework only backs every dma_buf fd with the anon_file struct file, + * i.e. all dma_bufs share the same file. + * + * Hence exporters need to setup their own file (and address_space) + * association by setting vma->vm_file and adjusting vma->vm_pgoff in + * the dma_buf mmap callback. In the specific case of a gem driver the + * exporter could use the shmem file already provided by gem (and set + * vm_pgoff = 0). Exporters can then zap ptes by unmapping the + * corresponding range of the struct address_space associated with their + * own file. + * + * This callback is optional. + * + * Returns: + * + * 0 on success or a negative error code on failure. + */ int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); void *(*vmap)(struct dma_buf *); -- cgit v1.2.3 From 56e3d1cd05cc7b24cfcae8714b0661bf607aaba3 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 15 Dec 2016 06:01:10 +0100 Subject: kref: prefer atomic_inc_not_zero to atomic_add_unless On most platforms, there exists this ifdef: #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) This makes this patch functionally useless. However, on PPC, there is actually an explicit definition of atomic_inc_not_zero with its own assembly that is slightly more optimized than atomic_add_unless. So, this patch changes kref to use atomic_inc_not_zero instead, for PPC and any future platforms that might provide an explicit implementation. This also puts this usage of kref more in line with a verbatim reading of the examples in Paul McKenney's paper [1] in the section titled "2.4 Atomic Counting With Check and Release Memory Barrier", which uses atomic_inc_not_zero. [1] http://open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2167.pdf Signed-off-by: Jason A. Donenfeld Reviewed-by: Thomas Hellstrom Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161215050110.3241-1-Jason@zx2c4.com --- include/linux/kref.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/kref.h b/include/linux/kref.h index e15828fd71f1..62f0a84ae94e 100644 --- a/include/linux/kref.h +++ b/include/linux/kref.h @@ -133,6 +133,6 @@ static inline int kref_put_mutex(struct kref *kref, */ static inline int __must_check kref_get_unless_zero(struct kref *kref) { - return atomic_add_unless(&kref->refcount, 1, 0); + return atomic_inc_not_zero(&kref->refcount); } #endif /* _KREF_H_ */ -- cgit v1.2.3 From cf4a7207b1cb4a3c3fe3aa11a83c9d673722a7f5 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 22 Dec 2016 14:45:14 +0000 Subject: lib: Add a simple prime number generator Prime numbers are interesting for testing components that use multiplies and divides, such as testing DRM's struct drm_mm alignment computations. v2: Move to lib/, add selftest v3: Fix initial constants (exclude 0/1 from being primes) v4: More RCU markup to keep 0day/sparse happy v5: Fix RCU unwind on module exit, add to kselftests v6: Tidy computation of bitmap size v7: for_each_prime_number_from() v8: Compose small-primes using BIT() for easier verification v9: Move rcu dance entirely into callers. v10: Improve quote for Betrand's Postulate (aka Chebyshev's theorem) Signed-off-by: Chris Wilson Cc: Lukas Wunner Reviewed-by: Joonas Lahtinen Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161222144514.3911-1-chris@chris-wilson.co.uk --- include/linux/prime_numbers.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 include/linux/prime_numbers.h (limited to 'include/linux') diff --git a/include/linux/prime_numbers.h b/include/linux/prime_numbers.h new file mode 100644 index 000000000000..14ec4f567342 --- /dev/null +++ b/include/linux/prime_numbers.h @@ -0,0 +1,37 @@ +#ifndef __LINUX_PRIME_NUMBERS_H +#define __LINUX_PRIME_NUMBERS_H + +#include + +bool is_prime_number(unsigned long x); +unsigned long next_prime_number(unsigned long x); + +/** + * for_each_prime_number - iterate over each prime upto a value + * @prime: the current prime number in this iteration + * @max: the upper limit + * + * Starting from the first prime number 2 iterate over each prime number up to + * the @max value. On each iteration, @prime is set to the current prime number. + * @max should be less than ULONG_MAX to ensure termination. To begin with + * @prime set to 1 on the first iteration use for_each_prime_number_from() + * instead. + */ +#define for_each_prime_number(prime, max) \ + for_each_prime_number_from((prime), 2, (max)) + +/** + * for_each_prime_number_from - iterate over each prime upto a value + * @prime: the current prime number in this iteration + * @from: the initial value + * @max: the upper limit + * + * Starting from @from iterate over each successive prime number up to the + * @max value. On each iteration, @prime is set to the current prime number. + * @max should be less than ULONG_MAX, and @from less than @max, to ensure + * termination. + */ +#define for_each_prime_number_from(prime, from, max) \ + for (prime = (from); prime <= (max); prime = next_prime_number(prime)) + +#endif /* !__LINUX_PRIME_NUMBERS_H */ -- cgit v1.2.3 From f641d3b536e559dd2bae9245ec2e7d86cdf623fd Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 29 Dec 2016 21:48:24 +0100 Subject: dma-buf: use preferred struct reference in kernel-doc sed -e 's/\( \* .*\)struct &\([_a-z]*\)/\1\&struct \2/' -i Originally I wasnt a friend of this style because I thought a line-break between the "&struct" and "foo" part would break it. But a quick test shows that " * &struct \n * foo\n" works pefectly well with current kernel-doc. So time to mass-apply these changes! Cc: Sumit Semwal Cc: Jani Nikula Cc: Chris Wilson Reviewed-by: David Herrmann Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1483044517-5770-4-git-send-email-daniel.vetter@ffwll.ch --- include/linux/dma-buf.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 57828154e440..4d61fc55278b 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -278,7 +278,7 @@ struct dma_buf_ops { * Shared dma buffers are reference counted using dma_buf_put() and * get_dma_buf(). * - * Device DMA access is handled by the separate struct &dma_buf_attachment. + * Device DMA access is handled by the separate &struct dma_buf_attachment. */ struct dma_buf { size_t size; @@ -355,7 +355,7 @@ struct dma_buf_export_info { * DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters * @name: export-info name * - * DEFINE_DMA_BUF_EXPORT_INFO macro defines the struct &dma_buf_export_info, + * DEFINE_DMA_BUF_EXPORT_INFO macro defines the &struct dma_buf_export_info, * zeroes it out and pre-populates exp_name in it. */ #define DEFINE_DMA_BUF_EXPORT_INFO(name) \ -- cgit v1.2.3 From e9b4d7b56f293ed4de9ff7d16759d33492f83180 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 29 Dec 2016 21:48:25 +0100 Subject: dma-buf: Use recommended structure member reference I just learned that &struct_name.member_name works and looks pretty even. It doesn't (yet) link to the member directly though, which would be really good for big structures or vfunc tables (where the per-member kerneldoc tends to be long). Cc: Sumit Semwal Cc: Jani Nikula Cc: Chris Wilson Reviewed-by: David Herrmann Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1483044517-5770-5-git-send-email-daniel.vetter@ffwll.ch --- include/linux/dma-buf.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 4d61fc55278b..bfb3704fc6fc 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -66,8 +66,8 @@ struct dma_buf_ops { * is not the case, and the allocation cannot be moved, it should also * fail the attach operation. * - * Any exporter-private housekeeping data can be stored in the priv - * pointer of &dma_buf_attachment structure. + * Any exporter-private housekeeping data can be stored in the + * &dma_buf_attachment.priv pointer. * * This callback is optional. * @@ -106,7 +106,7 @@ struct dma_buf_ops { * * Note that any specific buffer attributes required for this function * should get added to device_dma_parameters accessible via - * device->dma_params from the &dma_buf_attachment. The @attach callback + * &device.dma_params from the &dma_buf_attachment. The @attach callback * should also check these constraints. * * If this is being called for the first time, the exporter can now -- cgit v1.2.3 From d6c99f4bf093a58d3ab47caaec74b81f18bc4e3f Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 4 Jan 2017 14:12:21 +0000 Subject: dma-fence: Wrap querying the fence->status The fence->status is an optional field that is only valid once the fence has been signaled. (Driver may fill the fence->status with an error code prior to calling dma_fence_signal().) Given the restriction upon its validity, wrap querying of the fence->status into a helper dma_fence_get_status(). Signed-off-by: Chris Wilson Reviewed-by: Daniel Vetter Reviewed-by: Sumit Semwal Signed-off-by: Sumit Semwal Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-2-chris@chris-wilson.co.uk --- include/linux/dma-fence.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'include/linux') diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index d51a7d23c358..19f7af905182 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -378,6 +378,30 @@ static inline struct dma_fence *dma_fence_later(struct dma_fence *f1, return dma_fence_is_signaled(f2) ? NULL : f2; } +/** + * dma_fence_get_status_locked - returns the status upon completion + * @fence: [in] the dma_fence to query + * + * Drivers can supply an optional error status condition before they signal + * the fence (to indicate whether the fence was completed due to an error + * rather than success). The value of the status condition is only valid + * if the fence has been signaled, dma_fence_get_status_locked() first checks + * the signal state before reporting the error status. + * + * Returns 0 if the fence has not yet been signaled, 1 if the fence has + * been signaled without an error condition, or a negative error code + * if the fence has been completed in err. + */ +static inline int dma_fence_get_status_locked(struct dma_fence *fence) +{ + if (dma_fence_is_signaled_locked(fence)) + return fence->status < 0 ? fence->status : 1; + else + return 0; +} + +int dma_fence_get_status(struct dma_fence *fence); + signed long dma_fence_wait_timeout(struct dma_fence *, bool intr, signed long timeout); signed long dma_fence_wait_any_timeout(struct dma_fence **fences, -- cgit v1.2.3 From a009e975da5c7d42a7f5eaadc54946eb5f76c9af Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 4 Jan 2017 14:12:22 +0000 Subject: dma-fence: Introduce drm_fence_set_error() helper The dma_fence.error field (formerly known as dma_fence.status) is an optional field that may be set by drivers before calling dma_fence_signal(). The field can be used to indicate that the fence was completed in err rather than with success, and is visible to other consumers of the fence and to userspace via sync_file. This patch renames the field from status to error so that its meaning is hopefully more clear (and distinct from dma_fence_get_status() which is a composite between the error state and signal state) and adds a helper that validates the preconditions of when it is suitable to adjust the error field. Signed-off-by: Chris Wilson Reviewed-by: Daniel Vetter Reviewed-by: Sumit Semwal Signed-off-by: Sumit Semwal Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-3-chris@chris-wilson.co.uk --- include/linux/dma-fence.h | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 19f7af905182..6048fa404e57 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -47,7 +47,7 @@ struct dma_fence_cb; * can be compared to decide which fence would be signaled later. * @flags: A mask of DMA_FENCE_FLAG_* defined below * @timestamp: Timestamp when the fence was signaled. - * @status: Optional, only valid if < 0, must be set before calling + * @error: Optional, only valid if < 0, must be set before calling * dma_fence_signal, indicates that the fence has completed with an error. * * the flags member must be manipulated and read using the appropriate @@ -79,7 +79,7 @@ struct dma_fence { unsigned seqno; unsigned long flags; ktime_t timestamp; - int status; + int error; }; enum dma_fence_flag_bits { @@ -133,7 +133,7 @@ struct dma_fence_cb { * or some failure occurred that made it impossible to enable * signaling. True indicates successful enabling. * - * fence->status may be set in enable_signaling, but only when false is + * fence->error may be set in enable_signaling, but only when false is * returned. * * Calling dma_fence_signal before enable_signaling is called allows @@ -145,7 +145,7 @@ struct dma_fence_cb { * the second time will be a noop since it was already signaled. * * Notes on signaled: - * May set fence->status if returning true. + * May set fence->error if returning true. * * Notes on wait: * Must not be NULL, set to dma_fence_default_wait for default implementation. @@ -395,13 +395,33 @@ static inline struct dma_fence *dma_fence_later(struct dma_fence *f1, static inline int dma_fence_get_status_locked(struct dma_fence *fence) { if (dma_fence_is_signaled_locked(fence)) - return fence->status < 0 ? fence->status : 1; + return fence->error ?: 1; else return 0; } int dma_fence_get_status(struct dma_fence *fence); +/** + * dma_fence_set_error - flag an error condition on the fence + * @fence: [in] the dma_fence + * @error: [in] the error to store + * + * Drivers can supply an optional error status condition before they signal + * the fence, to indicate that the fence was completed due to an error + * rather than success. This must be set before signaling (so that the value + * is visible before any waiters on the signal callback are woken). This + * helper exists to help catching erroneous setting of #dma_fence.error. + */ +static inline void dma_fence_set_error(struct dma_fence *fence, + int error) +{ + BUG_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)); + BUG_ON(error >= 0 || error < -MAX_ERRNO); + + fence->error = error; +} + signed long dma_fence_wait_timeout(struct dma_fence *, bool intr, signed long timeout); signed long dma_fence_wait_any_timeout(struct dma_fence **fences, -- cgit v1.2.3