Messages in this thread Patch in this message | | | From | Noam Camus <> | Subject | [PATCH v1 05/20] ARC: rwlock: disable interrupts in !LLSC variant | Date | Sat, 31 Oct 2015 15:15:12 +0200 |
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From: Noam Camus <noamc@ezchip.com>
If we hold rw->lock_mutex and interrupt occures we may end up spinning on it for ever during softirq.
Below you may see an example for interrupt we get while nl_table_lock is holding its rw->lock_mutex and we spinned on it for ever.
The concept for the fix was taken from SPARC.
[2015-05-12 19:16:12] Stack Trace: [2015-05-12 19:16:12] arc_unwind_core+0xb8/0x11c [2015-05-12 19:16:12] dump_stack+0x68/0xac [2015-05-12 19:16:12] _raw_read_lock+0xa8/0xac [2015-05-12 19:16:12] netlink_broadcast_filtered+0x56/0x35c [2015-05-12 19:16:12] nlmsg_notify+0x42/0xa4 [2015-05-12 19:16:13] neigh_update+0x1fe/0x44c [2015-05-12 19:16:13] neigh_event_ns+0x40/0xa4 [2015-05-12 19:16:13] arp_process+0x46e/0x5a8 [2015-05-12 19:16:13] __netif_receive_skb_core+0x358/0x500 [2015-05-12 19:16:13] process_backlog+0x92/0x154 [2015-05-12 19:16:13] net_rx_action+0xb8/0x188 [2015-05-12 19:16:13] __do_softirq+0xda/0x1d8 [2015-05-12 19:16:14] irq_exit+0x8a/0x8c [2015-05-12 19:16:14] arch_do_IRQ+0x6c/0xa8 [2015-05-12 19:16:14] handle_interrupt_level1+0xe4/0xf0
Signed-off-by: Noam Camus <noamc@ezchip.com> Cc: Peter Zijlstra <peterz@infradead.org> --- arch/arc/include/asm/spinlock.h | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h index db8c59d..800e7c4 100644 --- a/arch/arc/include/asm/spinlock.h +++ b/arch/arc/include/asm/spinlock.h @@ -610,7 +610,9 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) static inline int arch_read_trylock(arch_rwlock_t *rw) { int ret = 0; + unsigned long flags; + local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); /* @@ -623,6 +625,7 @@ static inline int arch_read_trylock(arch_rwlock_t *rw) } arch_spin_unlock(&(rw->lock_mutex)); + local_irq_restore(flags); smp_mb(); return ret; @@ -632,7 +635,9 @@ static inline int arch_read_trylock(arch_rwlock_t *rw) static inline int arch_write_trylock(arch_rwlock_t *rw) { int ret = 0; + unsigned long flags; + local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); /* @@ -646,6 +651,7 @@ static inline int arch_write_trylock(arch_rwlock_t *rw) ret = 1; } arch_spin_unlock(&(rw->lock_mutex)); + local_irq_restore(flags); return ret; } @@ -664,16 +670,24 @@ static inline void arch_write_lock(arch_rwlock_t *rw) static inline void arch_read_unlock(arch_rwlock_t *rw) { + unsigned long flags; + + local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); rw->counter++; arch_spin_unlock(&(rw->lock_mutex)); + local_irq_restore(flags); } static inline void arch_write_unlock(arch_rwlock_t *rw) { + unsigned long flags; + + local_irq_save(flags); arch_spin_lock(&(rw->lock_mutex)); rw->counter = __ARCH_RW_LOCK_UNLOCKED__; arch_spin_unlock(&(rw->lock_mutex)); + local_irq_restore(flags); } #endif -- 1.7.1
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