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From: Peter Zijlstra <peterz@infradead.org>
To: Noam Camus <noamc@ezchip.com>
Cc: linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org,
	talz@ezchip.com, gilf@ezchip.com, cmetcalf@ezchip.com
Subject: Re: [PATCH v1 05/20] ARC: rwlock: disable interrupts in !LLSC variant
Date: Mon, 2 Nov 2015 10:16:39 +0100	[thread overview]
Message-ID: <20151102091639.GK17308@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1446297327-16298-6-git-send-email-noamc@ezchip.com>

On Sat, Oct 31, 2015 at 03:15:12PM +0200, Noam Camus wrote:
> 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>

It might make sense to note that this is a lock internal lock and since
the lock is free to be used from any context, the lock needs to be
IRQ-safe.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>


  reply	other threads:[~2015-11-02  9:16 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-31 13:15 [PATCH v1 00/20] eznps a new ARC platform Noam Camus
2015-10-31 13:15 ` [PATCH v1 01/20] Documentation: Add EZchip vendor to binding list Noam Camus
2015-10-31 13:15 ` [PATCH v1 02/20] clocksource: Add NPS400 timers driver Noam Camus
2015-11-01 20:44   ` Daniel Lezcano
2015-11-02  7:57     ` Noam Camus
2015-11-02 11:03   ` Vineet Gupta
2015-11-03 15:18     ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 03/20] irqchip: add nps Internal and external irqchips Noam Camus
2015-10-31 13:15 ` [PATCH v1 04/20] ARC: Set vmalloc size from configuration Noam Camus
2015-10-31 13:15 ` [PATCH v1 05/20] ARC: rwlock: disable interrupts in !LLSC variant Noam Camus
2015-11-02  9:16   ` Peter Zijlstra [this message]
2015-11-02  9:42   ` Vineet Gupta
2015-11-02 10:03     ` Peter Zijlstra
2015-10-31 13:15 ` [PATCH v1 06/20] ARC: Mark cpu online only after it has executed the per cpu init hook Noam Camus
2015-10-31 13:15 ` [PATCH v1 07/20] ARC: mm: use generic macros _BITUL() Noam Camus
2015-11-02  6:23   ` Vineet Gupta
2015-11-02  6:27     ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 08/20] ARC: Use res_service as entry point for secondaries Noam Camus
2015-11-02  6:38   ` Vineet Gupta
2015-11-02  8:05     ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 09/20] ARC: add CONFIG_CLKSRC_OF support to time_init() Noam Camus
2015-11-02  6:32   ` Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 10/20] ARC: [plat-eznps] Add eznps board defconfig and dts Noam Camus
2015-10-31 13:15 ` [PATCH v1 11/20] ARC: [plat-eznps] Add eznps platform Noam Camus
2015-11-02 10:56   ` Vineet Gupta
2015-11-03 15:59     ` Noam Camus
2015-11-04 12:38     ` Noam Camus
2015-11-05  5:09   ` Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 12/20] ARC: [plat-eznps] Use dedicated user stack top Noam Camus
2015-10-31 13:15 ` [PATCH v1 13/20] ARC: [plat-eznps] Use dedicated bitops/atomic/cmpxchg Noam Camus
2015-11-02 11:56   ` Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 14/20] ARC: [plat-eznps] Use dedicated SMP barriers Noam Camus
2015-11-02  8:02   ` Vineet Gupta
2015-11-02 13:08     ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 15/20] ARC: [plat-eznps] Use dedicated identity auxiliary register Noam Camus
2015-10-31 13:15 ` [PATCH v1 16/20] ARC: [plat-eznps] Use dedicated cpu_relax() Noam Camus
2015-11-02  7:54   ` Vineet Gupta
2015-11-02  9:21   ` Peter Zijlstra
2015-11-03 14:02     ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 17/20] ARC: [plat-eznps] Use dedicated COMMAND_LINE_SIZE Noam Camus
2015-10-31 13:15 ` [PATCH v1 18/20] ARC: [plat-eznps] define IPI_IRQ Noam Camus
2015-11-02  7:52   ` Vineet Gupta
2015-11-02 12:16     ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 19/20] ARC: [plat-eznps] replace sync with proper cpu barrier Noam Camus
2015-11-02  7:48   ` Vineet Gupta
2015-11-02  9:26     ` Peter Zijlstra
2015-11-17 13:48       ` [PATCH] ARC: remove SYNC from __switch_to() Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 20/20] ARC: Add eznps platform to Kconfig and Makefile Noam Camus
2015-11-02 11:06   ` Vineet Gupta
2015-11-03 15:32     ` Noam Camus
2015-11-04 15:35 ` [PATCH v1 00/20] eznps a new ARC platform Vineet Gupta
2015-11-04 15:53   ` Noam Camus
2015-11-04 17:42     ` Vineet Gupta
2015-11-07 10:52 ` [PATCH v2 00/19] " Noam Camus
2015-11-07 10:52 ` [PATCH v2 01/19] Documentation: Add EZchip vendor to binding list Noam Camus
2015-11-07 10:52 ` [PATCH v2 02/19] ARC: [plat-eznps] define IPI_IRQ Noam Camus
2015-11-07 10:52 ` [PATCH v2 03/19] clocksource: Add NPS400 timers driver Noam Camus
2015-11-07 11:26   ` Thomas Gleixner
2015-11-20 11:59     ` Noam Camus
2015-11-07 10:52 ` [PATCH v2 04/19] irqchip: add nps Internal and external irqchips Noam Camus
2015-11-07 11:38   ` Thomas Gleixner
2015-11-07 20:52     ` Noam Camus
2015-11-07 23:52       ` Thomas Gleixner
2015-11-07 10:52 ` [PATCH v2 05/19] ARC: Set vmalloc size from configuration Noam Camus
2015-11-07 10:52 ` [PATCH v2 06/19] ARC: rwlock: disable interrupts in !LLSC variant Noam Camus
2015-11-07 10:52 ` [PATCH v2 07/19] ARC: rename smp operation init_irq_cpu() to init_per_cpu() Noam Camus
2015-11-17 11:15   ` Vineet Gupta
2015-11-17 11:38     ` Noam Camus
2015-11-17 11:42       ` Vineet Gupta
2015-11-07 10:52 ` [PATCH v2 08/19] ARC: Mark secondary cpu online only after all HW setup is done Noam Camus
2015-11-17 11:17   ` Vineet Gupta
2015-11-07 10:52 ` [PATCH v2 09/19] ARC: add CONFIG_CLKSRC_OF support to time_init() Noam Camus
2015-11-07 10:52 ` [PATCH v2 10/19] ARC: [plat-eznps] Add eznps board defconfig and dts Noam Camus
2015-11-07 10:52 ` [PATCH v2 11/19] ARC: [plat-eznps] Add eznps platform Noam Camus
2015-11-07 10:52 ` [PATCH v2 12/19] ARC: [plat-eznps] Use dedicated user stack top Noam Camus
2015-11-07 10:52 ` [PATCH v2 13/19] ARC: [plat-eznps] Use dedicated atomic/bitops/cmpxchg Noam Camus
2015-11-07 10:52 ` [PATCH v2 14/19] ARC: [plat-eznps] Use dedicated SMP barriers Noam Camus
2015-11-07 10:52 ` [PATCH v2 15/19] ARC: [plat-eznps] Use dedicated identity auxiliary register Noam Camus
2015-11-07 10:52 ` [PATCH v2 16/19] ARC: [plat-eznps] Use dedicated cpu_relax() Noam Camus
2015-11-09 10:05   ` Peter Zijlstra
2015-11-09 10:22     ` Vineet Gupta
2015-11-09 10:45       ` Peter Zijlstra
2015-11-09 12:27         ` Vineet Gupta
2015-11-09 12:51           ` Peter Zijlstra
2015-11-07 10:52 ` [PATCH v2 17/19] ARC: [plat-eznps] Use dedicated COMMAND_LINE_SIZE Noam Camus
2015-11-07 10:52 ` [PATCH v2 18/19] ARC: [plat-eznps] replace sync with proper cpu barrier Noam Camus
2015-11-17 11:12   ` Vineet Gupta
2015-11-17 11:23     ` Peter Zijlstra
2015-11-17 11:37       ` Vineet Gupta
2015-11-17 12:22         ` Peter Zijlstra
2015-11-17 12:37           ` Vineet Gupta
2015-11-17 12:44             ` Peter Zijlstra
2015-11-17 13:32               ` Vineet Gupta
2015-11-17 13:59                 ` Peter Zijlstra
2015-11-07 10:52 ` [PATCH v2 19/19] ARC: Add eznps platform to Kconfig and Makefile Noam Camus

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