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| author | Andrea Parri <parri.andrea@gmail.com> | 2024-01-31 15:49:34 +0100 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-02-15 08:04:12 -0800 |
| commit | a14d11a0f5f4105e0df96811dfa81dc5f79fecba (patch) | |
| tree | 5b581014e1cbf4e437de5afb74e8a9bff9b9e8eb /kernel/sched | |
| parent | d6cfd1770f20392d7009ae1fdb04733794514fa9 (diff) | |
| download | linux-a14d11a0f5f4105e0df96811dfa81dc5f79fecba.tar.gz linux-a14d11a0f5f4105e0df96811dfa81dc5f79fecba.tar.bz2 linux-a14d11a0f5f4105e0df96811dfa81dc5f79fecba.zip | |
membarrier: Create Documentation/scheduler/membarrier.rst
To gather the architecture requirements of the "private/global
expedited" membarrier commands. The file will be expanded to
integrate further information about the membarrier syscall (as
needed/desired in the future). While at it, amend some related
inline comments in the membarrier codebase.
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/r/20240131144936.29190-3-parri.andrea@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 7 | ||||
| -rw-r--r-- | kernel/sched/membarrier.c | 8 |
2 files changed, 10 insertions, 5 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c4ca8085885a..a972628e7756 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6638,7 +6638,9 @@ static void __sched notrace __schedule(unsigned int sched_mode) * if (signal_pending_state()) if (p->state & @state) * * Also, the membarrier system call requires a full memory barrier - * after coming from user-space, before storing to rq->curr. + * after coming from user-space, before storing to rq->curr; this + * barrier matches a full barrier in the proximity of the membarrier + * system call exit. */ rq_lock(rq, &rf); smp_mb__after_spinlock(); @@ -6716,6 +6718,9 @@ static void __sched notrace __schedule(unsigned int sched_mode) * architectures where spin_unlock is a full barrier, * - switch_to() for arm64 (weakly-ordered, spin_unlock * is a RELEASE barrier), + * + * The barrier matches a full barrier in the proximity of + * the membarrier system call entry. */ ++*switch_count; diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 2ad881d07752..f3d91628d6b8 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -251,7 +251,7 @@ static int membarrier_global_expedited(void) return 0; /* - * Matches memory barriers around rq->curr modification in + * Matches memory barriers after rq->curr modification in * scheduler. */ smp_mb(); /* system call entry is not a mb. */ @@ -300,7 +300,7 @@ static int membarrier_global_expedited(void) /* * Memory barrier on the caller thread _after_ we finished - * waiting for the last IPI. Matches memory barriers around + * waiting for the last IPI. Matches memory barriers before * rq->curr modification in scheduler. */ smp_mb(); /* exit from system call is not a mb */ @@ -339,7 +339,7 @@ static int membarrier_private_expedited(int flags, int cpu_id) return 0; /* - * Matches memory barriers around rq->curr modification in + * Matches memory barriers after rq->curr modification in * scheduler. */ smp_mb(); /* system call entry is not a mb. */ @@ -415,7 +415,7 @@ out: /* * Memory barrier on the caller thread _after_ we finished - * waiting for the last IPI. Matches memory barriers around + * waiting for the last IPI. Matches memory barriers before * rq->curr modification in scheduler. */ smp_mb(); /* exit from system call is not a mb */ |