From a6fa941d94b411bbd2b6421ffbde6db3c93e65ab Mon Sep 17 00:00:00 2001
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: Mon, 20 Aug 2012 14:59:25 +0100
Subject: perf_event: Switch to internal refcount, fix race with close()
Don't mess with file refcounts (or keep a reference to file, for
that matter) in perf_event. Use explicit refcount of its own
instead. Deal with the race between the final reference to event
going away and new children getting created for it by use of
atomic_long_inc_not_zero() in inherit_event(); just have the
latter free what it had allocated and return NULL, that works
out just fine (children of siblings of something doomed are
created as singletons, same as if the child of leader had been
created and immediately killed).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120820135925.GG23464@ZenIV.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/perf_event.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'include/linux/perf_event.h')
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7602ccb3f40e..ad04dfcd6f35 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -926,7 +926,7 @@ struct perf_event {
struct hw_perf_event hw;
struct perf_event_context *ctx;
- struct file *filp;
+ atomic_long_t refcount;
/*
* These accumulate total time (in nanoseconds) that children
--
cgit
From 500ad2d8b01390c98bc6dce068bccfa9534b8212 Mon Sep 17 00:00:00 2001
From: "K.Prasad" <Prasad.Krishnan@gmail.com>
Date: Thu, 2 Aug 2012 13:46:35 +0530
Subject: 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>
---
include/linux/perf_event.h | 2 ++
kernel/events/core.c | 2 +-
kernel/events/hw_breakpoint.c | 11 ++++++++++-
3 files changed, 13 insertions(+), 2 deletions(-)
(limited to 'include/linux/perf_event.h')
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ad04dfcd6f35..33ed9d605f91 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -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
diff --git a/kernel/events/core.c b/kernel/events/core.c
index efef4282b8e8..7fee567153f0 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 bb38c4d3ee12..9a7b487c6fe2 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -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;
--
cgit