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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Amol Lad <amol@verismonetworks.com>
Cc: linux kernel <linux-kernel@vger.kernel.org>,
	kernel Janitors <kernel-janitors@lists.osdl.org>
Subject: Re: [KJ] [PATCH] drivers/char/riscom8.c:
Date: Sat, 14 Oct 2006 14:20:02 +0000	[thread overview]
Message-ID: <1160835602.5732.30.camel@localhost.localdomain> (raw)
In-Reply-To: <1160739628.19143.376.camel@amol.verismonetworks.com>

Ar Gwe, 2006-10-13 am 17:10 +0530, ysgrifennodd Amol Lad:
> Removed save_flags()/cli()/sti() and used (light weight) spin locks
> 

Three things I see that look problematic

1. The irq locking isn't doing anything as the IRQ handler itself is not
taking the lock
2. If the irq handler itself dumbly locks to fix this then we get
tty_flip_buffer_push() re-entering the other code paths and deadlocking
if low latency is enabled
3. Some of the use of local_save/spin_lock_irq seems over-clever and
unneeded

Fixable but how about we just delete the file since it has been broken
for ages and nobody can be using it ?

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WARNING: multiple messages have this Message-ID (diff)
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Amol Lad <amol@verismonetworks.com>
Cc: linux kernel <linux-kernel@vger.kernel.org>,
	kernel Janitors <kernel-janitors@lists.osdl.org>
Subject: Re: [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal
Date: Sat, 14 Oct 2006 15:20:02 +0100	[thread overview]
Message-ID: <1160835602.5732.30.camel@localhost.localdomain> (raw)
In-Reply-To: <1160739628.19143.376.camel@amol.verismonetworks.com>

Ar Gwe, 2006-10-13 am 17:10 +0530, ysgrifennodd Amol Lad:
> Removed save_flags()/cli()/sti() and used (light weight) spin locks
> 

Three things I see that look problematic

1. The irq locking isn't doing anything as the IRQ handler itself is not
taking the lock
2. If the irq handler itself dumbly locks to fix this then we get
tty_flip_buffer_push() re-entering the other code paths and deadlocking
if low latency is enabled
3. Some of the use of local_save/spin_lock_irq seems over-clever and
unneeded

Fixable but how about we just delete the file since it has been broken
for ages and nobody can be using it ?


  parent reply	other threads:[~2006-10-14 14:20 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-13 11:40 [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Amol Lad
2006-10-13 11:52 ` [KJ] [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() Amol Lad
2006-10-13 11:56 ` [KJ] [PATCH] drivers/char/riscom8.c: Arjan van de Ven
2006-10-13 11:56   ` [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Arjan van de Ven
2006-10-13 12:36   ` Amol Lad
2006-10-13 12:48     ` [KJ] [PATCH] drivers/char/riscom8.c: Amol Lad
2006-10-13 15:00 ` Alan Cox
2006-10-13 15:00   ` [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Alan Cox
2006-10-14  7:39   ` Amol Lad
2006-10-14  7:51     ` [KJ] [PATCH] drivers/char/riscom8.c: Amol Lad
2006-10-14 12:18     ` Alan Cox
2006-10-14 12:18       ` [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Alan Cox
2006-10-14 14:20 ` Alan Cox [this message]
2006-10-14 14:20   ` Alan Cox
2006-10-14 17:49   ` [KJ] [PATCH] drivers/char/riscom8.c: Matthew Wilcox
2006-10-14 17:49     ` [KJ] [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Matthew Wilcox
2006-10-14 18:41     ` [KJ] [PATCH] Alan Cox
2006-10-14 18:41       ` [KJ] [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Alan Cox
2006-10-14 18:50       ` [KJ] [PATCH] drivers/char/riscom8.c: Matthew Wilcox
2006-10-14 18:50         ` [KJ] [PATCH] drivers/char/riscom8.c: save_flags()/cli()/sti() removal Matthew Wilcox
2006-10-16  4:32   ` Amol Lad
2006-10-16  4:44     ` [KJ] [PATCH] drivers/char/riscom8.c: Amol Lad

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