tracing: Fix syscall_*regfunc() vs copy_process() race (4af4206b) · Commits · 戴 / test

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 Cc: stable@vger.kernel.org # 2.6.33 Fixes: "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>

include/trace/syscall.h

+15 −0

Original line number	Diff line number	Diff line
		@@ -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 */

kernel/fork.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1487,7 +1487,9 @@ 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)

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