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| author | Peter Maydell <peter.maydell@linaro.org> | 2023-03-07 17:02:06 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2023-03-07 17:02:06 +0000 |
| commit | 7b0f0aa55fd292fa3489755a3a896e496c51ea86 (patch) | |
| tree | 07bec628ff71b6ab5a1b6a117d41cb8b46117367 /include/qemu | |
| parent | 9832009d9dd2386664c15cc70f6e6bfe062be8bd (diff) | |
| parent | 6229438cca037d42f44a96d38feb15cb102a444f (diff) | |
| download | qemu-7b0f0aa55fd292fa3489755a3a896e496c51ea86.zip qemu-7b0f0aa55fd292fa3489755a3a896e496c51ea86.tar.gz qemu-7b0f0aa55fd292fa3489755a3a896e496c51ea86.tar.bz2 | |
Merge tag 'for-upstream-mb' of https://gitlab.com/bonzini/qemu into staging
* Fix missing memory barriers
* Fix comments about memory ordering
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# gpg: Signature made Tue 07 Mar 2023 11:40:26 GMT
# gpg: using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg: issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
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* tag 'for-upstream-mb' of https://gitlab.com/bonzini/qemu:
async: clarify usage of barriers in the polling case
async: update documentation of the memory barriers
physmem: add missing memory barrier
qemu-coroutine-lock: add smp_mb__after_rmw()
aio-wait: switch to smp_mb__after_rmw()
edu: add smp_mb__after_rmw()
qemu-thread-win32: cleanup, fix, document QemuEvent
qemu-thread-posix: cleanup, fix, document QemuEvent
qatomic: add smp_mb__before/after_rmw()
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'include/qemu')
| -rw-r--r-- | include/qemu/atomic.h | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index 874134f..f85834e 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -245,6 +245,20 @@ #define smp_wmb() smp_mb_release() #define smp_rmb() smp_mb_acquire() +/* + * SEQ_CST is weaker than the older __sync_* builtins and Linux + * kernel read-modify-write atomics. Provide a macro to obtain + * the same semantics. + */ +#if !defined(QEMU_SANITIZE_THREAD) && \ + (defined(__i386__) || defined(__x86_64__) || defined(__s390x__)) +# define smp_mb__before_rmw() signal_barrier() +# define smp_mb__after_rmw() signal_barrier() +#else +# define smp_mb__before_rmw() smp_mb() +# define smp_mb__after_rmw() smp_mb() +#endif + /* qatomic_mb_read/set semantics map Java volatile variables. They are * less expensive on some platforms (notably POWER) than fully * sequentially consistent operations. @@ -259,7 +273,8 @@ #if !defined(QEMU_SANITIZE_THREAD) && \ (defined(__i386__) || defined(__x86_64__) || defined(__s390x__)) /* This is more efficient than a store plus a fence. */ -# define qatomic_mb_set(ptr, i) ((void)qatomic_xchg(ptr, i)) +# define qatomic_mb_set(ptr, i) \ + ({ (void)qatomic_xchg(ptr, i); smp_mb__after_rmw(); }) #else # define qatomic_mb_set(ptr, i) \ ({ qatomic_store_release(ptr, i); smp_mb(); }) |