diff options
Diffstat (limited to 'man2/membarrier.2')
| -rw-r--r-- | man2/membarrier.2 | 64 |
1 files changed, 55 insertions, 9 deletions
diff --git a/man2/membarrier.2 b/man2/membarrier.2 index e38650c05..a0e67edc8 100644 --- a/man2/membarrier.2 +++ b/man2/membarrier.2 @@ -30,7 +30,7 @@ membarrier \- issue memory barriers on a set of threads .PP .B #include <linux/membarrier.h> .PP -.BI "int membarrier(int " cmd ", int " flags ");" +.BI "int membarrier(int " cmd ", unsigned int " flags ", int " cpu_id ); .fi .PP .IR Note : @@ -165,6 +165,29 @@ core command prior to using it. Register the process's intent to use .BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE . .TP +.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ " (since Linux 5.10)" +Ensure the caller thread, upon return from system call, that all its +running thread siblings have any currently running rseq critical sections +restarted if +.I flags +parameter is 0; if +.I flags +parameter is +.BR MEMBARRIER_CMD_FLAG_CPU , +then this operation is performed only on CPU indicated by +.IR cpu_id . +This guarantee is provided only for threads in +the same process as the calling thread. +.IP +RSEQ membarrier is only available in the "private expedited" form. +.IP +A process must register its intent to use the private expedited rseq +command prior to using it. +.TP +.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ " (since Linux 5.10)" +Register the process's intent to use +.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ . +.TP .BR MEMBARRIER_CMD_SHARED " (since Linux 4.3)" This is an alias for .BR MEMBARRIER_CMD_GLOBAL @@ -172,7 +195,21 @@ that exists for header backward compatibility. .PP The .I flags -argument is currently unused and must be specified as 0. +argument must be specified as 0 unless the command is +.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ , +in which case +.I flags +can be either 0 or +.BR MEMBARRIER_CMD_FLAG_CPU . +.PP +The +.I cpu_id +argument is ignored unless +.I flags +is +.BR MEMBARRIER_CMD_FLAG_CPU , +in which case it must specify the CPU targeted by this membarrier +command. .PP All memory accesses performed in program order from each targeted thread are guaranteed to be ordered with respect to @@ -187,7 +224,7 @@ to represent explicit memory barriers forcing full memory ordering across the barrier, we have the following ordering table for each pairing of .IR barrier() , -.BR membarrier () +.BR membarrier (), and .IR smp_mb() . The pair ordering is detailed as (O: ordered, X: not ordered): @@ -251,7 +288,16 @@ commands. The .BR membarrier () system call was added in Linux 4.3. -.\" +.PP +Before Linux 5.10, the prototype for +.BR membarrier () +was: +.PP +.in +4n +.EX +.BI "int membarrier(int " cmd ", int " flags ); +.EE +.in .SH CONFORMING TO .BR membarrier () is Linux-specific. @@ -350,9 +396,9 @@ becomes: static volatile int a, b; static int -membarrier(int cmd, int flags) +membarrier(int cmd, unsigned int flags, int cpu_id) { - return syscall(__NR_membarrier, cmd, flags); + return syscall(__NR_membarrier, cmd, flags, cpu_id); } static int @@ -362,7 +408,7 @@ init_membarrier(void) /* Check that membarrier() is supported. */ - ret = membarrier(MEMBARRIER_CMD_QUERY, 0); + ret = membarrier(MEMBARRIER_CMD_QUERY, 0, 0); if (ret < 0) { perror("membarrier"); return \-1; @@ -389,7 +435,7 @@ static void slow_path(int *read_a) { b = 1; - membarrier(MEMBARRIER_CMD_GLOBAL, 0); + membarrier(MEMBARRIER_CMD_GLOBAL, 0, 0); *read_a = a; } @@ -423,7 +469,7 @@ main(int argc, char **argv) .EE .in .SH COLOPHON -This page is part of release 5.09 of the Linux +This page is part of release 5.10 of the Linux .I man-pages project. A description of the project, |