diff options
76 files changed, 5930 insertions, 2780 deletions
diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt index 0f1fdedf36bb..0f1ffa03db09 100644 --- a/Documentation/atomic_t.txt +++ b/Documentation/atomic_t.txt @@ -271,3 +271,97 @@ WRITE_ONCE. Thus: SC *y, t; is allowed. + + +CMPXCHG vs TRY_CMPXCHG +---------------------- + + int atomic_cmpxchg(atomic_t *ptr, int old, int new); + bool atomic_try_cmpxchg(atomic_t *ptr, int *oldp, int new); + +Both provide the same functionality, but try_cmpxchg() can lead to more +compact code. The functions relate like: + + bool atomic_try_cmpxchg(atomic_t *ptr, int *oldp, int new) + { + int ret, old = *oldp; + ret = atomic_cmpxchg(ptr, old, new); + if (ret != old) + *oldp = ret; + return ret == old; + } + +and: + + int atomic_cmpxchg(atomic_t *ptr, int old, int new) + { + (void)atomic_try_cmpxchg(ptr, &old, new); + return old; + } + +Usage: + + old = atomic_read(&v); old = atomic_read(&v); + for (;;) { do { + new = func(old); new = func(old); + tmp = atomic_cmpxchg(&v, old, new); } while (!atomic_try_cmpxchg(&v, &old, new)); + if (tmp == old) + break; + old = tmp; + } + +NB. try_cmpxchg() also generates better code on some platforms (notably x86) +where the function more closely matches the hardware instruction. + + +FORWARD PROGRESS +---------------- + +In general strong forward progress is expected of all unconditional atomic +operations -- those in the Arithmetic and Bitwise classes and xchg(). However +a fair amount of code also requires forward progress from the conditional +atomic operations. + +Specifically 'simple' cmpxchg() loops are expected to not starve one another +indefinitely. However, this is not evident on LL/SC architectures, because +while an LL/SC architecure 'can/should/must' provide forward progress +guarantees between competing LL/SC sections, such a guarantee does not +transfer to cmpxchg() implemented using LL/SC. Consider: + + old = atomic_read(&v); + do { + new = func(old); + } while (!atomic_try_cmpxchg(&v, &old, new)); + +which on LL/SC becomes something like: + + old = atomic_read(&v); + do { + new = func(old); + } while (!({ + volatile asm ("1: LL %[oldval], %[v]\n" + " CMP %[oldval], %[old]\n" + " BNE 2f\n" + " SC %[new], %[v]\n" + " BNE 1b\n" + "2:\n" + : [oldval] "=&r" (oldval), [v] "m" (v) + : [old] "r" (old), [new] "r" (new) + : "memory"); + success = (oldval == old); + if (!success) + old = oldval; + success; })); + +However, even the forward branch from the failed compare can cause the LL/SC +to fail on some architectures, let alone whatever the compiler makes of the C +loop body. As a result there is no guarantee what so ever the cacheline +containing @v will stay on the local CPU and progress is made. + +Even native CAS architectures can fail to provide forward progress for their +primitive (See Sparc64 for an example). + +Such implementations are strongly encouraged to add exponential backoff loops +to a failed CAS in order to ensure some progress. Affected architectures are +also strongly encouraged to inspect/audit the atomic fallbacks, refcount_t and +their locking primitives. diff --git a/drivers/staging/media/atomisp/pci/atomisp_ioctl.c b/drivers/staging/media/atomisp/pci/atomisp_ioctl.c index 6f5fe5092154..c8a625667e81 100644 --- a/drivers/staging/media/atomisp/pci/atomisp_ioctl.c +++ b/drivers/staging/media/atomisp/pci/atomisp_ioctl.c @@ -1904,8 +1904,8 @@ int __atomisp_streamoff(struct file *file, void *fh, enum v4l2_buf_type type) dev_dbg(isp->dev, "Stop stream on pad %d for asd%d\n", atomisp_subdev_source_pad(vdev), asd->index); - BUG_ON(!rt_mutex_is_locked(&isp->mutex)); - BUG_ON(!mutex_is_locked(&isp->streamoff_mutex)); + lockdep_assert_held(&isp->mutex); + lockdep_assert_held(&isp->streamoff_mutex); if (type != V4L2_BUF_TYPE_VIDEO_CAPTURE) { dev_dbg(isp->dev, "unsupported v4l2 buf type\n"); diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h deleted file mode 100644 index 073cf40f431b..000000000000 --- a/include/asm-generic/atomic-long.h +++ /dev/null @@ -1,1014 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 - -// Generated by scripts/atomic/gen-atomic-long.sh -// DO NOT MODIFY THIS FILE DIRECTLY - -#ifndef _ASM_GENERIC_ATOMIC_LONG_H -#define _ASM_GENERIC_ATOMIC_LONG_H - -#include <linux/compiler.h> -#include <asm/types.h> - -#ifdef CONFIG_64BIT -typedef atomic64_t atomic_long_t; -#define ATOMIC_LONG_INIT(i) ATOMIC64_INIT(i) -#define atomic_long_cond_read_acquire atomic64_cond_read_acquire -#define atomic_long_cond_read_relaxed atomic64_cond_read_relaxed -#else -typedef atomic_t atomic_long_t; -#define ATOMIC_LONG_INIT(i) ATOMIC_INIT(i) -#define atomic_long_cond_read_acquire atomic_cond_read_acquire -#define atomic_long_cond_read_relaxed atomic_cond_read_relaxed -#endif - -#ifdef CONFIG_64BIT - -static __always_inline long -atomic_long_read(const atomic_long_t *v) -{ - return atomic64_read(v); -} - -static __always_inline long -atomic_long_read_acquire(const atomic_long_t *v) -{ - return atomic64_read_acquire(v); -} - -static __always_inline void -atomic_long_set(atomic_long_t *v, long i) -{ - atomic64_set(v, i); -} - -static __always_inline void -atomic_long_set_release(atomic_long_t *v, long i) -{ - atomic64_set_release(v, i); -} - -static __always_inline void -atomic_long_add(long i, atomic_long_t *v) -{ - atomic64_add(i, v); -} - -static __always_inline long -atomic_long_add_return(long i, atomic_long_t *v) -{ - return atomic64_add_return(i, v); -} - -static __always_inline long -atomic_long_add_return_acquire(long i, atomic_long_t *v) -{ - return atomic64_add_return_acquire(i, v); -} - -static __always_inline long -atomic_long_add_return_release(long i, atomic_long_t *v) -{ - return atomic64_add_return_release(i, v); -} - -static __always_inline long -atomic_long_add_return_relaxed(long i, atomic_long_t *v) -{ - return atomic64_add_return_relaxed(i, v); -} - -static __always_inline long -atomic_long_fetch_add(long i, atomic_long_t *v) -{ - return atomic64_fetch_add(i, v); -} - -static __always_inline long -atomic_long_fetch_add_acquire(long i, atomic_long_t *v) -{ - return atomic64_fetch_add_acquire(i, v); -} - -static __always_inline long -atomic_long_fetch_add_release(long i, atomic_long_t *v) -{ - return atomic64_fetch_add_release(i, v); -} - -static __always_inline long -atomic_long_fetch_add_relaxed(long i, atomic_long_t *v) -{ - return atomic64_fetch_add_relaxed(i, v); -} - -static __always_inline void -atomic_long_sub(long i, atomic_long_t *v) -{ - atomic64_sub(i, v); -} - -static __always_inline long -atomic_long_sub_return(long i, atomic_long_t *v) -{ - return atomic64_sub_return(i, v); -} - -static __always_inline long -atomic_long_sub_return_acquire(long i, atomic_long_t *v) -{ - return atomic64_sub_return_acquire(i, v); -} - -static __always_inline long -atomic_long_sub_return_release(long i, atomic_long_t *v) -{ - return atomic64_sub_return_release(i, v); -} - -static __always_inline long -atomic_long_sub_return_relaxed(long i, atomic_long_t *v) -{ - return atomic64_sub_return_relaxed(i, v); -} - -static __always_inline long -atomic_long_fetch_sub(long i, atomic_long_t *v) -{ - return atomic64_fetch_sub(i, v); -} - -static __always_inline long -atomic_long_fetch_sub_acquire(long i, atomic_long_t *v) -{ - return atomic64_fetch_sub_acquire(i, v); -} - -static __always_inline long -atomic_long_fetch_sub_release(long i, atomic_long_t *v) -{ - return atomic64_fetch_sub_release(i, v); -} - -static __always_inline long -atomic_long_fetch_sub_relaxed(long i, atomic_long_t *v) -{ - return atomic64_fetch_sub_relaxed(i, v); -} - -static __always_inline void -atomic_long_inc(atomic_long_t *v) -{ - atomic64_inc(v); -} - -static __always_inline long -atomic_long_inc_return(atomic_long_t *v) -{ - return atomic64_inc_return(v); -} - -static __always_inline long -atomic_long_inc_return_acquire(atomic_long_t *v) -{ - return atomic64_inc_return_acquire(v); -} - -static __always_inline long -atomic_long_inc_return_release(atomic_long_t *v) -{ - return atomic64_inc_return_release(v); -} - -static __always_inline long -atomic_long_inc_return_relaxed(atomic_long_t *v) -{ - return atomic64_inc_return_relaxed(v); -} - -static __always_inline long -atomic_long_fetch_inc(atomic_long_t *v) -{ - return atomic64_fetch_inc(v); -} - -static __always_inline long -atomic_long_fetch_inc_acquire(atomic_long_t *v) -{ - return atomic64_fetch_inc_acquire(v); -} - -static __always_inline long -atomic_long_fetch_inc_release(atomic_long_t *v) -{ - return atomic64_fetch_inc_release(v); -} - -static __always_inline long -atomic_long_fetch_inc_relaxed(atomic_long_t *v) -{ - return atomic64_fetch_inc_relaxed(v); -} - -static __always_inline void -atomic_long_dec(atomic_long_t *v) -{ - atomic64_dec(v); -} - -static __always_inline long -atomic_long_dec_return(atomic_long_t *v) -{ - return atomic64_dec_return(v); -} - -static __always_inline long -atomic_long_dec_return_acquire(atomic_long_t *v) -{ - return atomic64_dec_return_acquire(v); -} - -static __always_inline long -atomic_long_dec_return_release(atomic_long_t *v) -{ - return atomic64_dec_return_release(v); -} - -static __always_inline long -atomic_long_dec_return_relaxed(atomic_long_t *v) -{ - return atomic64_dec_return_relaxed(v); -} - -static __always_inline long -atomic_long_fetch_dec(atomic_long_t *v) -{ - return atomic64_fetch_dec(v); -} - -static __always_inline long -atomic_long_fetch_dec_acquire(atomic_long_t *v) -{ - return atomic64_fetch_dec_acquire(v); -} - -static __always_inline long -atomic_long_fetch_dec_release(atomic_long_t *v) -{ - return atomic64_fetch_dec_release(v); -} - -static __always_inline long -atomic_long_fetch_dec_relaxed(atomic_long_t *v) -{ - return atomic64_fetch_dec_relaxed(v); -} - -static __always_inline void -atomic_long_and(long i, atomic_long_t *v) -{ - atomic64_and(i, v); -} - -static __always_inline long -atomic_long_fetch_and(long i, atomic_long_t *v) -{ - return atomic64_fetch_and(i, v); -} - -static __always_inline long -atomic_long_fetch_and_acquire(long i, atomic_long_t *v) -{ - return atomic64_fetch_and_acquire(i, v); -} - -static __always_inline long -atomic_long_fetch_and_release(long i, atomic_long_t *v) -{ - return atomic64_fetch_and_release(i, v); -} - -static __always_inline long -atomic_long_fetch_and_relaxed(long i, atomic_long_t *v) -{ - return atomic64_fetch_and_relaxed(i, v); -} - -static __always_inline void -atomic_long_andnot(long i, atomic_long_t *v) -{ - atomic64_andnot(i, v); -} - -static __always_inline long -atomic_long_fetch_andnot(long i, atomic_long_t *v) -{ - return atomic64_fetch_andnot(i, v); -} - -static __always_inline long -atomic_long_fetch_andnot_acquire(long i, atomic_long_t *v) -{ - return atomic64_fetch_andnot_acquire(i, v); -} - -static __always_inline long -atomic_long_fetch_andnot_release(long i, atomic_long_t *v) -{ - return atomic64_fetch_andnot_release(i, v); -} - -static __always_inline long -atomic_long_fetch_andnot_relaxed(long i, atomic_long_t *v) -{ - return atomic64_fetch_andnot_relaxed(i, v); -} - -static __always_inline void -atomic_long_or(long i, atomic_long_t *v) -{ - atomic64_or(i, v); -} - -static __always_inline long -atomic_long_fetch_or(long i, atomic_long_t *v) -{ - return atomic64_fetch_or(i, v); -} - -static __always_inline long -atomic_long_fetch_or_acquire(long i, atomic_long_t *v) -{ - return atomic64_fetch_or_acquire(i, v); -} - -static __always_inline long -atomic_long_fetch_or_release(long i, atomic_long_t *v) -{ - return atomic64_fetch_or_release(i, v); -} - -static __always_inline long -atomic_long_fetch_or_relaxed(long i, atomic_long_t *v) -{ - return atomic64_fetch_or_relaxed(i, v); -} - -static __always_inline void -atomic_long_xor(long i, atomic_long_t *v) -{ - atomic64_xor(i, v); -} - -static __always_inline long -atomic_long_fetch_xor(long i, atomic_long_t *v) -{ - return atomic64_fetch_xor(i, v); -} - -static __always_inline long -atomic_long_fetch_xor_acquire(long i, atomic_long_t *v) -{ - return atomic64_fetch_xor_acquire(i, v); -} - -static __always_inline long -atomic_long_fetch_xor_release(long i, atomic_long_t *v) -{ - return atomic64_fetch_xor_release(i, v); -} - -static __always_inline long -atomic_long_fetch_xor_relaxed(long i, atomic_long_t *v) -{ - return atomic64_fetch_xor_relaxed(i, v); -} - -static __always_inline long -atomic_long_xchg(atomic_long_t *v, long i) -{ - return atomic64_xchg(v, i); -} - -static __always_inline long -atomic_long_xchg_acquire(atomic_long_t *v, long i) -{ - return atomic64_xchg_acquire(v, i); -} - -static __always_inline long -atomic_long_xchg_release(atomic_long_t *v, long i) -{ - return atomic64_xchg_release(v, i); -} - -static __always_inline long -atomic_long_xchg_relaxed(atomic_long_t *v, long i) -{ - return atomic64_xchg_relaxed(v, i); -} - -static __always_inline long -atomic_long_cmpxchg(atomic_long_t *v, long old, long new) -{ - return atomic64_cmpxchg(v, old, new); -} - -static __always_inline lon |