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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2017-10-19 13:30:15 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2017-10-19 22:13:40 -0400
commita961e40917fb14614d368d8bc9782ca4d6a8cd11 (patch)
treebb2778144007d317d197b4f6cb5816ae91afb300 /fs
parent96f893abc87bd29339c973edf6068a064cb8a756 (diff)
membarrier: Provide register expedited private command
This introduces a "register private expedited" membarrier command which allows eventual removal of important memory barrier constraints on the scheduler fast-paths. It changes how the "private expedited" membarrier command (new to 4.14) is used from user-space. This new command allows processes to register their intent to use the private expedited command. This affects how the expedited private command introduced in 4.14-rc is meant to be used, and should be merged before 4.14 final. Processes are now required to register before using MEMBARRIER_CMD_PRIVATE_EXPEDITED, otherwise that command returns EPERM. This fixes a problem that arose when designing requested extensions to sys_membarrier() to allow JITs to efficiently flush old code from instruction caches. Several potential algorithms are much less painful if the user register intent to use this functionality early on, for example, before the process spawns the second thread. Registering at this time removes the need to interrupt each and every thread in that process at the first expedited sys_membarrier() system call. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/exec.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 5470d3c1892a..3e14ba25f678 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1802,6 +1802,7 @@ static int do_execveat_common(int fd, struct filename *filename,
/* execve succeeded */
current->fs->in_exec = 0;
current->in_execve = 0;
+ membarrier_execve(current);
acct_update_integrals(current);
task_numa_free(current);
free_bprm(bprm);