| Message ID | 20120324103030.GG29067@lizard (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Sat, Mar 24, 2012 at 01:48:23PM +0100, Peter Zijlstra wrote: > On Sat, 2012-03-24 at 14:30 +0400, Anton Vorontsov wrote: > > Traversing the tasks requires holding tasklist_lock, otherwise it > > is unsafe. > > No it doesn't, it either requires tasklist_lock or rcu_read_lock(). Well, currently the code does neither. :-)
diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c index 4d93dff..66d754c 100644 --- a/arch/um/kernel/reboot.c +++ b/arch/um/kernel/reboot.c @@ -4,6 +4,7 @@ */ #include "linux/sched.h" +#include "linux/spinlock.h" #include "linux/slab.h" #include "kern_util.h" #include "os.h" @@ -22,6 +23,7 @@ static void kill_off_processes(void) struct task_struct *p; int pid; + read_lock(&tasklist_lock); for_each_process(p) { if (p->mm == NULL) continue; @@ -29,6 +31,7 @@ static void kill_off_processes(void) pid = p->mm->context.id.u.pid; os_kill_ptraced_process(pid, 1); } + read_unlock(&tasklist_lock); } }
Traversing the tasks requires holding tasklist_lock, otherwise it is unsafe. p.s. However, I'm not sure that calling os_kill_ptraced_process() in the atomic context is correct. It seem to work, but please take a closer look. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> --- arch/um/kernel/reboot.c | 3 +++ 1 file changed, 3 insertions(+)