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authorStanislaw Gruszka <sgruszka@redhat.com>2009-11-17 14:14:12 -0800
committerThomas Gleixner <tglx@linutronix.de>2009-11-18 16:32:12 +0100
commit8747d793fc5c4d3e4decd41d55f6dc24498dd5f5 (patch)
tree78983389e7e4656c755e81a97b5e08de0e640e04 /kernel/itimer.c
parent0696b711e4be45fa104c12329f617beb29c03f78 (diff)
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itimers: Fix racy writes to cpu_itimer fields
incr_error and error fields of struct cpu_itimer are used when calculating next timer tick in check_cpu_itimers() and should not be modified without tsk->sighand->siglock taken. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> LKML-Reference: <1253802903-979-1-git-send-email-sgruszka@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/itimer.c')
-rw-r--r--kernel/itimer.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/itimer.c b/kernel/itimer.c
index b03451ede528..d802883153da 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -146,6 +146,7 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
{
cputime_t cval, nval, cinterval, ninterval;
s64 ns_ninterval, ns_nval;
+ u32 error, incr_error;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
nval = timeval_to_cputime(&value->it_value);
@@ -153,8 +154,8 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
ninterval = timeval_to_cputime(&value->it_interval);
ns_ninterval = timeval_to_ns(&value->it_interval);
- it->incr_error = cputime_sub_ns(ninterval, ns_ninterval);
- it->error = cputime_sub_ns(nval, ns_nval);
+ error = cputime_sub_ns(nval, ns_nval);
+ incr_error = cputime_sub_ns(ninterval, ns_ninterval);
spin_lock_irq(&tsk->sighand->siglock);
@@ -168,6 +169,8 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
}
it->expires = nval;
it->incr = ninterval;
+ it->error = error;
+ it->incr_error = incr_error;
trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
ITIMER_VIRTUAL : ITIMER_PROF, value, nval);