AUDIT: Reduce contention in audit_serial()
... by generating serial numbers only if an audit context is actually
_used_, rather than doing so at syscall entry even when the context
isn't necessarily marked auditable.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
diff --git a/kernel/audit.c b/kernel/audit.c
index 27ffcf36..d321e25 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -625,7 +625,9 @@
unsigned int ret;
spin_lock_irqsave(&serial_lock, flags);
- ret = serial++;
+ do {
+ ret = ++serial;
+ } while (unlikely(!ret));
spin_unlock_irqrestore(&serial_lock, flags);
return ret;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 242d45e..46b45ab 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -984,7 +984,7 @@
if (likely(state == AUDIT_DISABLED))
return;
- context->serial = audit_serial();
+ context->serial = 0;
context->ctime = CURRENT_TIME;
context->in_syscall = 1;
context->auditable = !!(state == AUDIT_RECORD_CONTEXT);
@@ -1138,6 +1138,8 @@
void auditsc_get_stamp(struct audit_context *ctx,
struct timespec *t, unsigned int *serial)
{
+ if (!ctx->serial)
+ ctx->serial = audit_serial();
t->tv_sec = ctx->ctime.tv_sec;
t->tv_nsec = ctx->ctime.tv_nsec;
*serial = ctx->serial;
