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authorOleg Nesterov <oleg@redhat.com>2014-04-13 20:58:54 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-06 18:49:20 -0700
commit0c3351a0a4815ea566d3febf82033b6c55ed4a2d (patch)
tree6aaeb576ba3bda684481e2ca0d4b185b7b0ff6a6
parente3293b8639a90b7227be9c273af0a45015c499bb (diff)
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@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/trace/syscall.h15
-rw-r--r--kernel/fork.c2
2 files changed, 17 insertions, 0 deletions
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 31966a4fb8cc..51b72d8a8498 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>
@@ -54,4 +55,18 @@ int perf_sysexit_enable(struct ftrace_event_call *call);
void perf_sysexit_disable(struct ftrace_event_call *call);
#endif
+#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 afac42b8889c..621c547dabb1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1441,7 +1441,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
total_forks++;
spin_unlock(&current->sighand->siglock);
+ syscall_tracepoint_update(p);
write_unlock_irq(&tasklist_lock);
+
proc_fork_connector(p);
cgroup_post_fork(p);
if (clone_flags & CLONE_THREAD)