[tip:perf/core] hw breakpoints: Fix pid namespace bug

[tip-bot for Matt Helsley]

Commit-ID:  d958077d007d98125766d11e82da2fd6497b91d6
Gitweb:     http://git.kernel.org/tip/d958077d007d98125766d11e82da2fd6497b91d6
Author:     Matt Helsley <matthltc@xxxxxxxxxx>
AuthorDate: Mon, 13 Sep 2010 13:01:18 -0700
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 15 Sep 2010 10:43:59 +0200

hw breakpoints: Fix pid namespace bug

Hardware breakpoints can't be registered within pid namespaces
because tsk->pid is passed rather than the pid in the current
namespace.

(See https://bugzilla.kernel.org/show_bug.cgi?id=17281 )

This is a quick fix demonstrating the problem but is not the
best method of solving the problem since passing pids internally
is not the best way to avoid pid namespace bugs. Subsequent patches
will show a better solution.

Much thanks to Frederic Weisbecker <fweisbec@xxxxxxxxx> for doing the
bulk of the work finding this bug.

Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Robin Green <greenrd@xxxxxxxxxxx>
Cc: Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <f63454af09fb1915717251570423eb9ddd338340.1284407762.git.matthltc@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 kernel/hw_breakpoint.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 3b2aaff..6122f02 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -433,7 +433,8 @@ register_user_hw_breakpoint(struct perf_event_attr *attr,
 			    perf_overflow_handler_t triggered,
 			    struct task_struct *tsk)
 {
-	return perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
+	return perf_event_create_kernel_counter(attr, -1, task_pid_vnr(tsk),
+						triggered);
 }
 EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
 
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