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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-04-20 01:16:02 (GMT) |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-05-27 19:56:16 (GMT) |
| commit | e90328b87eeff91574c18815bd6991b03bd6ecc0 (patch) | |
| tree | 4c5b7d82d6160ab7931fa4bbb79e371c0b909bbe /arch/x86/kernel | |
| parent | 7d0ae8086b828311250c6afdf800b568ac9bd693 (diff) | |
| download | linux-e90328b87eeff91574c18815bd6991b03bd6ecc0.tar.xz | |
mce: Stop using array-index-based RCU primitives
Because mce is arch-specific x86 code, there is little or no
performance benefit of using rcu_dereference_index_check() over using
smp_load_acquire(). It also turns out that mce is the only place that
array-index-based RCU is used, and it would be convenient to drop
this portion of the RCU API.
This patch therefore changes rcu_dereference_index_check() uses to
smp_load_acquire(), but keeping the lockdep diagnostics, and also
changes rcu_access_index() uses to READ_ONCE().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: linux-edac@vger.kernel.org
Cc: Tony Luck <tony.luck@intel.com>
Acked-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/mce.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index e535533..1fd04a0 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -53,9 +53,12 @@ static DEFINE_MUTEX(mce_chrdev_read_mutex); #define rcu_dereference_check_mce(p) \ - rcu_dereference_index_check((p), \ - rcu_read_lock_sched_held() || \ - lockdep_is_held(&mce_chrdev_read_mutex)) +({ \ + rcu_lockdep_assert(rcu_read_lock_sched_held() || \ + lockdep_is_held(&mce_chrdev_read_mutex), \ + "suspicious rcu_dereference_check_mce() usage"); \ + smp_load_acquire(&(p)); \ +}) #define CREATE_TRACE_POINTS #include <trace/events/mce.h> @@ -1884,7 +1887,7 @@ out: static unsigned int mce_chrdev_poll(struct file *file, poll_table *wait) { poll_wait(file, &mce_chrdev_wait, wait); - if (rcu_access_index(mcelog.next)) + if (READ_ONCE(mcelog.next)) return POLLIN | POLLRDNORM; if (!mce_apei_read_done && apei_check_mce()) return POLLIN | POLLRDNORM; |