[3.11.y.z extended stable] Patch "tracing: Fix syscall_*regfunc() vs copy_process() race" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Thu Jul 10 11:18:09 UTC 2014
This is a note to let you know that I have just added a patch titled
tracing: Fix syscall_*regfunc() vs copy_process() race
to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 1399807739636805c38d4e14dd77cf887778b21c Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg at redhat.com>
Date: Sun, 13 Apr 2014 20:58:54 +0200
Subject: tracing: Fix syscall_*regfunc() vs copy_process() race
commit 4af4206be2bd1933cae20c2b6fb2058dbc887f7c upstream.
syscall_regfunc() and syscall_unregfunc() should set/clear
TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race
with copy_process() and miss the new child which was not added to
the process/thread lists yet.
Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT
under tasklist.
Link: http://lkml.kernel.org/p/20140413185854.GB20668@redhat.com
Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints"
Acked-by: Frederic Weisbecker <fweisbec at gmail.com>
Acked-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg at redhat.com>
Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
include/trace/syscall.h | 15 +++++++++++++++
kernel/fork.c | 2 ++
2 files changed, 17 insertions(+)
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index fed853f3d7aa..9674145e2f6a 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -4,6 +4,7 @@
#include <linux/tracepoint.h>
#include <linux/unistd.h>
#include <linux/ftrace_event.h>
+#include <linux/thread_info.h>
#include <asm/ptrace.h>
@@ -32,4 +33,18 @@ struct syscall_metadata {
struct ftrace_event_call *exit_event;
};
+#if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS)
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+ if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
+ set_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+ else
+ clear_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+}
+#else
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+}
+#endif
+
#endif /* _TRACE_SYSCALL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 2782836d8adc..8c8cb29ebc95 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1491,7 +1491,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
total_forks++;
spin_unlock(¤t->sighand->siglock);
+ syscall_tracepoint_update(p);
write_unlock_irq(&tasklist_lock);
+
proc_fork_connector(p);
cgroup_post_fork(p);
if (clone_flags & CLONE_THREAD)
--
1.9.1
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