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perf/hwpb: Invoke __perf_event_disable() if interrupts are already disabled 

While debugging a warning message on PowerPC while using hardware
breakpoints, it was discovered that when perf_event_disable is invoked
through hw_breakpoint_handler function with interrupts disabled, a
subsequent IPI in the code path would trigger a WARN_ON_ONCE message in
smp_call_function_single function.

This patch calls __perf_event_disable() when interrupts are already
disabled, instead of perf_event_disable().

Reported-by: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>
Signed-off-by: K.Prasad <Prasad.Krishnan@gmail.com>
[naveen.n.rao@linux.vnet.ibm.com: v3: Check to make sure we target current task]
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120802081635.5811.17737.stgit@localhost.localdomain
[ Fixed build error on MIPS. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
K.Prasad 2012-08-02 13:46:35 +05:30 committed by Ingo Molnar
parent 3ec18cd8b8
commit 500ad2d8b0
3 changed files with 13 additions and 2 deletions
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2
include/linux/perf_event.h
View File

@ -1296,6 +1296,7 @@ extern int perf_swevent_get_recursion_context(void);
extern void perf_swevent_put_recursion_context(int rctx);
extern void perf_event_enable(struct perf_event *event);
extern void perf_event_disable(struct perf_event *event);
extern int __perf_event_disable(void *info);
extern void perf_event_task_tick(void);
#else
static inline void
@ -1334,6 +1335,7 @@ static inline int perf_swevent_get_recursion_context(void) { return -1; }
static inline void perf_swevent_put_recursion_context(int rctx) { }
static inline void perf_event_enable(struct perf_event *event) { }
static inline void perf_event_disable(struct perf_event *event) { }
static inline int __perf_event_disable(void *info) { return -1; }
static inline void perf_event_task_tick(void) { }
#endif

2
kernel/events/core.c
View File

@ -1253,7 +1253,7 @@ retry:
/*
* Cross CPU call to disable a performance event
*/
static int __perf_event_disable(void *info)
int __perf_event_disable(void *info)
{
struct perf_event *event = info;
struct perf_event_context *ctx = event->ctx;

11
kernel/events/hw_breakpoint.c
View File

@ -453,7 +453,16 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att
int old_type = bp->attr.bp_type;
int err = 0;
perf_event_disable(bp);
/*
* modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it
* will not be possible to raise IPIs that invoke __perf_event_disable.
* So call the function directly after making sure we are targeting the
* current task.
*/
if (irqs_disabled() && bp->ctx && bp->ctx->task == current)
__perf_event_disable(bp);
else
perf_event_disable(bp);
bp->attr.bp_addr = attr->bp_addr;
bp->attr.bp_type = attr->bp_type;