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From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Yishai Hadas <yishaih@dev.mellanox.co.il>
Cc: Yishai Hadas <yishaih@mellanox.com>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"jackm@mellanox.com" <jackm@mellanox.com>,
	Majd Dibbiny <majd@mellanox.com>
Subject: Re: [PATCH 3/5] net/mlx4: fix some error handling in mlx4_multi_func_init()
Date: Wed, 10 Feb 2016 19:15:20 +0100	[thread overview]
Message-ID: <87twlgtosn.fsf@rasmusvillemoes.dk> (raw)
In-Reply-To: <56BB0577.8000000@dev.mellanox.co.il> (Yishai Hadas's message of "Wed, 10 Feb 2016 11:40:07 +0200")

On Wed, Feb 10 2016, Yishai Hadas <yishaih@dev.mellanox.co.il> wrote:

>> @@ -2429,7 +2429,7 @@ err_thread:
>>   	flush_workqueue(priv->mfunc.master.comm_wq);
>>   	destroy_workqueue(priv->mfunc.master.comm_wq);
>>   err_slaves:
>> -	while (--i) {
>> +	while (i--) {
>
> This fix is wrong as it hits the case that i arrived the last value
> then below code will access to a non valid entry in the array.
>
> The expected fix should be:
> while (--i >= 0)
>

Huh? They're completely equivalent (given that i is necessarily
non-negative before we evaluate the loop condition). I don't really care
either way, but git grep says that 'while (i--)' is 5 times more common
than 'while (--i >= 0)'.

Rasmus

WARNING: multiple messages have this Message-ID (diff)
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Yishai Hadas <yishaih@dev.mellanox.co.il>
Cc: Yishai Hadas <yishaih@mellanox.com>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"jackm\@mellanox.com" <jackm@mellanox.com>,
	Majd Dibbiny <majd@mellanox.com>
Subject: Re: [PATCH 3/5] net/mlx4: fix some error handling in mlx4_multi_func_init()
Date: Wed, 10 Feb 2016 19:15:20 +0100	[thread overview]
Message-ID: <87twlgtosn.fsf@rasmusvillemoes.dk> (raw)
In-Reply-To: <56BB0577.8000000@dev.mellanox.co.il> (Yishai Hadas's message of "Wed, 10 Feb 2016 11:40:07 +0200")

On Wed, Feb 10 2016, Yishai Hadas <yishaih@dev.mellanox.co.il> wrote:

>> @@ -2429,7 +2429,7 @@ err_thread:
>>   	flush_workqueue(priv->mfunc.master.comm_wq);
>>   	destroy_workqueue(priv->mfunc.master.comm_wq);
>>   err_slaves:
>> -	while (--i) {
>> +	while (i--) {
>
> This fix is wrong as it hits the case that i arrived the last value
> then below code will access to a non valid entry in the array.
>
> The expected fix should be:
> while (--i >= 0)
>

Huh? They're completely equivalent (given that i is necessarily
non-negative before we evaluate the loop condition). I don't really care
either way, but git grep says that 'while (i--)' is 5 times more common
than 'while (--i >= 0)'.

Rasmus

  reply	other threads:[~2016-02-10 18:15 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-09 20:11 [PATCH 0/5] pre-decrement in error paths considered harmful Rasmus Villemoes
2016-02-09 20:11 ` Rasmus Villemoes
2016-02-09 20:11 ` [PATCH 1/5] drm/gma500: fix error path in gma_intel_setup_gmbus() Rasmus Villemoes
2016-02-10  6:41   ` Andy Shevchenko
2016-02-10  6:41     ` Andy Shevchenko
2016-02-10  7:26     ` Daniel Vetter
2016-02-10  7:26       ` Daniel Vetter
2016-02-09 20:11 ` [PATCH 2/5] drm/i915: fix error path in intel_setup_gmbus() Rasmus Villemoes
2016-02-09 20:11   ` Rasmus Villemoes
2016-02-09 20:27   ` Jani Nikula
2016-02-09 20:27     ` Jani Nikula
2016-02-10  8:56     ` Jani Nikula
2016-02-10  8:56       ` Jani Nikula
2016-02-09 20:11 ` [PATCH 3/5] net/mlx4: fix some error handling in mlx4_multi_func_init() Rasmus Villemoes
2016-02-10  9:40   ` Yishai Hadas
2016-02-10 18:15     ` Rasmus Villemoes [this message]
2016-02-10 18:15       ` Rasmus Villemoes
2016-02-11  9:29       ` Jack Morgenstein
2016-02-11  9:29         ` Jack Morgenstein
2016-02-11 10:20         ` Jack Morgenstein
2016-02-11 16:02   ` Doug Ledford
2016-02-09 20:11 ` [PATCH 4/5] net: sxgbe: fix error paths in sxgbe_platform_probe() Rasmus Villemoes
2016-03-08 20:44   ` Rasmus Villemoes
2016-03-22 19:47     ` Rasmus Villemoes
2016-03-26 21:24       ` [PATCH] " Rasmus Villemoes
2016-03-27  8:22         ` Francois Romieu
2016-03-27 21:40           ` Rasmus Villemoes
2016-03-28  2:39           ` David Miller
2016-03-28  2:40         ` David Miller
2016-02-09 20:11 ` [PATCH 5/5] mm/backing-dev.c: fix error path in wb_init() Rasmus Villemoes
2016-02-09 20:11   ` Rasmus Villemoes

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