diff options
| author | Mathieu Desnoyers <[email protected]> | 2016-11-03 10:29:28 -0600 |
|---|---|---|
| committer | Paul E. McKenney <[email protected]> | 2017-01-23 11:32:16 -0800 |
| commit | 907565337ebf998a68cb5c5b2174ce5e5da065eb (patch) | |
| tree | 5e5e3a5e43b3755f906bbc26bd20da6dd1dbe878 | |
| parent | 4d4f88fa235f7f9ef8213564dc1804144332238b (diff) | |
Fix: Disable sys_membarrier when nohz_full is enabled
Userspace applications should be allowed to expect the membarrier system
call with MEMBARRIER_CMD_SHARED command to issue memory barriers on
nohz_full CPUs, but synchronize_sched() does not take those into
account.
Given that we do not want unrelated processes to be able to affect
real-time sensitive nohz_full CPUs, simply return ENOSYS when membarrier
is invoked on a kernel with enabled nohz_full CPUs.
Signed-off-by: Mathieu Desnoyers <[email protected]>
CC: Josh Triplett <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: <[email protected]> [3.10+]
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Rik van Riel <[email protected]>
Acked-by: Lai Jiangshan <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
| -rw-r--r-- | kernel/membarrier.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/membarrier.c b/kernel/membarrier.c index 536c727a56e9..9f9284f37f8d 100644 --- a/kernel/membarrier.c +++ b/kernel/membarrier.c @@ -16,6 +16,7 @@ #include <linux/syscalls.h> #include <linux/membarrier.h> +#include <linux/tick.h> /* * Bitmask made from a "or" of all commands within enum membarrier_cmd, @@ -51,6 +52,9 @@ */ SYSCALL_DEFINE2(membarrier, int, cmd, int, flags) { + /* MEMBARRIER_CMD_SHARED is not compatible with nohz_full. */ + if (tick_nohz_full_enabled()) + return -ENOSYS; if (unlikely(flags)) return -EINVAL; switch (cmd) { |