Subject: [patch] lockdep: fix seqlock_init()
From: Ingo Molnar <[email protected]>
seqlock_init() needs to use spin_lock_init() for dynamic locks, so that
lockdep is notified about the presence of a new lock.
(this is a fallout of the recent networking merge, which started using
the so-far unused seqlock_init() API.)
This fix solves the following lockdep-internal warning on current -git:
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
[<c0104fd9>] dump_trace+0x63/0x1e8
[<c0105177>] show_trace_log_lvl+0x19/0x2e
[<c010557e>] show_trace+0x12/0x14
[<c0105594>] dump_stack+0x14/0x16
[<c0142992>] __lock_acquire+0x10c/0x9f9
[<c0143564>] lock_acquire+0x56/0x72
[<c03c514f>] _spin_lock+0x35/0x42
[<c0369875>] neigh_destroy+0x9d/0x12e
[<c036a1d5>] neigh_periodic_timer+0x10a/0x15c
[<c01302a5>] run_timer_softirq+0x126/0x18e
[<c012c530>] __do_softirq+0x6b/0xe6
[<c0106404>] do_softirq+0x64/0xd2
[<c012c249>] ksoftirqd+0x82/0x138
[<c01398f1>] kthread+0xb2/0xd7
[<c0104c1b>] kernel_thread_helper+0x7/0x10
Signed-off-by: Ingo Molnar <[email protected]>
---
include/linux/seqlock.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
Index: linux-hres-timers.q/include/linux/seqlock.h
===================================================================
--- linux-hres-timers.q.orig/include/linux/seqlock.h
+++ linux-hres-timers.q/include/linux/seqlock.h
@@ -44,8 +44,11 @@ typedef struct {
#define SEQLOCK_UNLOCKED \
__SEQLOCK_UNLOCKED(old_style_seqlock_init)
-#define seqlock_init(x) \
- do { *(x) = (seqlock_t) __SEQLOCK_UNLOCKED(x); } while (0)
+#define seqlock_init(x) \
+ do { \
+ (x)->sequence = 0; \
+ spin_lock_init(&(x)->lock); \
+ } while (0)
#define DEFINE_SEQLOCK(x) \
seqlock_t x = __SEQLOCK_UNLOCKED(x)
-
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