| Message ID | 20220225073351.3565619-1-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | dma-fance: Add dma_fence_assert_in_signalling_section | expand |
Am 25.02.22 um 08:33 schrieb Daniel Vetter: > Useful for checking for dma-fence signalling annotations since they > don't quite nest as freely as we'd like to. > > Cc: Matthew Brost <matthew.brost@intel.com> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > Cc: Sumit Semwal <sumit.semwal@linaro.org> > Cc: Gustavo Padovan <gustavo@padovan.org> > Cc: "Christian König" <christian.koenig@amd.com> > Cc: linux-media@vger.kernel.org > Cc: linaro-mm-sig@lists.linaro.org > --- > drivers/dma-buf/dma-fence.c | 19 +++++++++++++++++++ > include/linux/dma-fence.h | 2 ++ > 2 files changed, 21 insertions(+) > > diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c > index 066400ed8841..2b7c3fc965e6 100644 > --- a/drivers/dma-buf/dma-fence.c > +++ b/drivers/dma-buf/dma-fence.c > @@ -307,6 +307,25 @@ bool dma_fence_begin_signalling(void) > } > EXPORT_SYMBOL(dma_fence_begin_signalling); > > +/** > + * dma_fence_assert_in_signalling_section - check fence signalling annotations > + * > + * Since dma_fence_begin_signalling() and dma_fence_end_signalling() are built > + * using lockdep annotations they have limitations on how freely they can be > + * nested. Specifically, they cannot be on both inside and outside of locked > + * sections, which in practice means the annotations often have to be pushed out > + * to the top level callers. > + * > + * To ensure low-level functions are only called with the correction > + * annotations, this function can be used to check for that. I think I need a concrete example to understand what this is good for. Christian. > + */ > +void dma_fence_assert_in_signalling_section(void) > +{ > + if (!in_atomic()) > + lockdep_assert(lock_is_held(&dma_fence_lockdep_map)); > +} > +EXPORT_SYMBOL(dma_fence_assert_in_signalling_section); > + > /** > * dma_fence_end_signalling - end a critical DMA fence signalling section > * @cookie: opaque cookie from dma_fence_begin_signalling() > diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h > index 775cdc0b4f24..7179a5692f72 100644 > --- a/include/linux/dma-fence.h > +++ b/include/linux/dma-fence.h > @@ -356,6 +356,7 @@ dma_fence_get_rcu_safe(struct dma_fence __rcu **fencep) > > #ifdef CONFIG_LOCKDEP > bool dma_fence_begin_signalling(void); > +void dma_fence_assert_in_signalling_section(void); > void dma_fence_end_signalling(bool cookie); > void __dma_fence_might_wait(void); > #else > @@ -363,6 +364,7 @@ static inline bool dma_fence_begin_signalling(void) > { > return true; > } > +static inline void dma_fence_assert_in_signalling_section(void) {} > static inline void dma_fence_end_signalling(bool cookie) {} > static inline void __dma_fence_might_wait(void) {} > #endif
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 066400ed8841..2b7c3fc965e6 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -307,6 +307,25 @@ bool dma_fence_begin_signalling(void) } EXPORT_SYMBOL(dma_fence_begin_signalling); +/** + * dma_fence_assert_in_signalling_section - check fence signalling annotations + * + * Since dma_fence_begin_signalling() and dma_fence_end_signalling() are built + * using lockdep annotations they have limitations on how freely they can be + * nested. Specifically, they cannot be on both inside and outside of locked + * sections, which in practice means the annotations often have to be pushed out + * to the top level callers. + * + * To ensure low-level functions are only called with the correction + * annotations, this function can be used to check for that. + */ +void dma_fence_assert_in_signalling_section(void) +{ + if (!in_atomic()) + lockdep_assert(lock_is_held(&dma_fence_lockdep_map)); +} +EXPORT_SYMBOL(dma_fence_assert_in_signalling_section); + /** * dma_fence_end_signalling - end a critical DMA fence signalling section * @cookie: opaque cookie from dma_fence_begin_signalling() diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 775cdc0b4f24..7179a5692f72 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -356,6 +356,7 @@ dma_fence_get_rcu_safe(struct dma_fence __rcu **fencep) #ifdef CONFIG_LOCKDEP bool dma_fence_begin_signalling(void); +void dma_fence_assert_in_signalling_section(void); void dma_fence_end_signalling(bool cookie); void __dma_fence_might_wait(void); #else @@ -363,6 +364,7 @@ static inline bool dma_fence_begin_signalling(void) { return true; } +static inline void dma_fence_assert_in_signalling_section(void) {} static inline void dma_fence_end_signalling(bool cookie) {} static inline void __dma_fence_might_wait(void) {} #endif
Useful for checking for dma-fence signalling annotations since they don't quite nest as freely as we'd like to. Cc: Matthew Brost <matthew.brost@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Gustavo Padovan <gustavo@padovan.org> Cc: "Christian König" <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org --- drivers/dma-buf/dma-fence.c | 19 +++++++++++++++++++ include/linux/dma-fence.h | 2 ++ 2 files changed, 21 insertions(+)