From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: fweisbec@gmail.com, paulus@samba.org, a.p.zijlstra@chello.nl
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com,
emachado@linux.vnet.ibm.com, acme@ghostprotocols.net,
prasad.krishnan@gmail.com
Subject: [PATCH v2 RESEND] Hardware breakpoints: Invoke __perf_event_disable() if interrupts are already disabled
Date: Wed, 18 Jul 2012 16:00:46 +0530 [thread overview]
Message-ID: <20120718103046.7512.8326.stgit@localhost.localdomain> (raw)
In-Reply-To: <20120706101653.7515.23309.stgit@localhost.localdomain>
Please find v2 of the patch from Prasad, based on Peter Zijlstra's
feedback. This applies on top of v3.5-rc7. This has been tested and
found to work fine by Edjunior.
Regards,
Naveen
______
From: K.Prasad <Prasad.Krishnan@gmail.com>
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>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
include/linux/perf_event.h | 2 ++
kernel/events/core.c | 2 +-
kernel/events/hw_breakpoint.c | 10 +++++++++-
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 45db49f..c289ba0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1292,6 +1292,7 @@ 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
@@ -1330,6 +1331,7 @@ 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) { }
static inline void perf_event_task_tick(void) { }
#endif
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d7d71d6..0ad0fc9 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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;
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index bb38c4d..483f14a 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -453,7 +453,15 @@ 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.
+ */
+ if (irqs_disabled())
+ __perf_event_disable(bp);
+ else
+ perf_event_disable(bp);
bp->attr.bp_addr = attr->bp_addr;
bp->attr.bp_type = attr->bp_type;
next prev parent reply other threads:[~2012-07-18 10:31 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-11 6:02 [Patch][perf] Invoke __perf_event_disable without an IPI K.Prasad
2012-06-11 11:13 ` Peter Zijlstra
2012-06-12 6:06 ` K.Prasad
2012-06-12 9:12 ` Peter Zijlstra
2012-07-06 9:52 ` [PATCH v2] Hardware breakpoints: Invoke __perf_event_disable() if interrupts are already disabled Naveen N. Rao
2012-07-06 10:18 ` Naveen N. Rao
2012-07-18 10:30 ` Naveen N. Rao [this message]
2012-07-18 11:57 ` [PATCH v2 RESEND] " Frederic Weisbecker
2012-07-19 11:16 ` Naveen N. Rao
2012-07-25 11:32 ` Naveen N. Rao
2012-07-31 13:41 ` Frederic Weisbecker
2012-08-02 8:16 ` [PATCH v3] " Naveen N. Rao
2012-08-15 17:37 ` Naveen N. Rao
2012-08-15 18:42 ` Frederic Weisbecker
2012-08-16 8:16 ` Peter Zijlstra
2012-08-29 2:45 ` Naveen N. Rao
2012-09-04 18:53 ` [tip:perf/urgent] perf/hwpb: " tip-bot for K.Prasad
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