Messages in this thread Patch in this message | | | Subject | Re: 2.6.19-rc5: lockdep warnings starting irattach | From | Peter Zijlstra <> | Date | Mon, 20 Nov 2006 10:04:46 +0100 |
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On Sat, 2006-11-18 at 16:12 +0300, Andrey Borzenkov wrote:
> ============================================= > [ INFO: possible recursive locking detected ] > 2.6.19-rc5-2avb #2 > - --------------------------------------------- > pppd/26425 is trying to acquire lock: > (&hashbin->hb_spinlock){....}, at: [<dfdea87a>] irlmp_slsap_inuse+0x5a/0x170 > [irda] > > but task is already holding lock: > (&hashbin->hb_spinlock){....}, at: [<dfdea857>] irlmp_slsap_inuse+0x37/0x170 > [irda] > > other info that might help us debug this: > 1 lock held by pppd/26425: > #0: (&hashbin->hb_spinlock){....}, at: [<dfdea857>] > irlmp_slsap_inuse+0x37/0x170 [irda] > > stack backtrace: > [<c010413c>] dump_trace+0x1cc/0x200 > [<c010418a>] show_trace_log_lvl+0x1a/0x30 > [<c01047f2>] show_trace+0x12/0x20 > [<c01048c9>] dump_stack+0x19/0x20 > [<c01346ca>] __lock_acquire+0x8fa/0xc20 > [<c0134d2d>] lock_acquire+0x5d/0x80 > [<c02a851c>] _spin_lock+0x2c/0x40 > [<dfdea87a>] irlmp_slsap_inuse+0x5a/0x170 [irda] > [<dfdebab2>] irlmp_open_lsap+0x62/0x180 [irda] > [<dfdf35d1>] irttp_open_tsap+0x181/0x230 [irda] > [<dfdc0c3d>] ircomm_open_tsap+0x5d/0xa0 [ircomm] > [<dfdc05d8>] ircomm_open+0xb8/0xd0 [ircomm] > [<dfdd0477>] ircomm_tty_open+0x4f7/0x570 [ircomm_tty] > [<c020bbe4>] tty_open+0x174/0x340 > [<c016bd69>] chrdev_open+0x89/0x170 > [<c0167bd6>] __dentry_open+0xa6/0x1d0 > [<c0167da5>] nameidata_to_filp+0x35/0x40 > [<c0167df9>] do_filp_open+0x49/0x50 > [<c0167e47>] do_sys_open+0x47/0xd0 > [<c0167f0c>] sys_open+0x1c/0x20 > [<c010307d>] sysenter_past_esp+0x56/0x8d > [<b7f86410>] 0xb7f86410 > =======================
The comment at the nesting lock says:
/* Careful for priority inversions here ! * irlmp->links is never taken while another IrDA * spinlock is held, so we are safe. Jean II */
So, under the assumption the author was right, it just needs a lockdep annotation.
(depends on patches in -mm for spin_lock_irqsave_nested())
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- net/irda/irlmp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6-mm/net/irda/irlmp.c =================================================================== --- linux-2.6-mm.orig/net/irda/irlmp.c 2006-11-20 09:54:50.000000000 +0100 +++ linux-2.6-mm/net/irda/irlmp.c 2006-11-20 09:57:39.000000000 +0100 @@ -1678,7 +1678,7 @@ static int irlmp_slsap_inuse(__u8 slsap_ * every IrLAP connection and check every LSAP associated with each * the connection. */ - spin_lock_irqsave(&irlmp->links->hb_spinlock, flags); + spin_lock_irqsave_nested(&irlmp->links->hb_spinlock, flags, 1); lap = (struct lap_cb *) hashbin_get_first(irlmp->links); while (lap != NULL) { IRDA_ASSERT(lap->magic == LMP_LAP_MAGIC, goto errlap;);
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