On 06/19, Steven Rostedt wrote: > > On Thu, 19 Jun 2014 17:03:00 +0200 > Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > > > Argh... but it seems that that patch really needs a fix? > > > > - #ifdef CONFIG_TRACEPOINTS > > + #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS > > > > or even > > - #ifdef CONFIG_TRACEPOINTS > > + #if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS) > > > > or I am totally confused? > > I think the second one is needed. Agreed... see the updated patch below. Please tell me if I should another "[PATCH]" email or resend 2-3 as well. Sorry for inconvenience. ------------------------------------------------------------------------------- Subject: [PATCH] tracing: Fix syscall_*regfunc() vs copy_process() race 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@xxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx # 2.6.33 Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints" Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> --- include/trace/syscall.h | 15 +++++++++++++++ kernel/fork.c | 2 ++ 2 files changed, 17 insertions(+), 0 deletions(-) diff --git a/include/trace/syscall.h b/include/trace/syscall.h index fed853f..9674145 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 cafea61..f7417f5 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1485,7 +1485,9 @@ 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) -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe ecryptfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
