Re: [PATCH v2] cw1200: fix incorrect check to determine if no element is found in list

From: Kalle Valo <kvalo@kernel.org>
To: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Cc: pizza@shaftnet.org, davem@davemloft.net, kuba@kernel.org,
	pabeni@redhat.com, linville@tuxdriver.com,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, jakobkoschel@gmail.com,
	Xiaomeng Tong <xiam0nd.tong@gmail.com>
Subject: Re: [PATCH v2] cw1200: fix incorrect check to determine if no element is found in list
Date: Tue, 12 Apr 2022 13:51:21 +0000 (UTC)	[thread overview]
Message-ID: <164977147986.6629.2901483762629864309.kvalo@kernel.org> (raw)
In-Reply-To: <20220320035436.11293-1-xiam0nd.tong@gmail.com>

Xiaomeng Tong <xiam0nd.tong@gmail.com> wrote:

> The bug is here: "} else if (item) {".
> 
> The list iterator value will *always* be set and non-NULL by
> list_for_each_entry(), so it is incorrect to assume that the iterator
> value will be NULL if the list is empty or no element is found in list.
> 
> Use a new value 'iter' as the list iterator, while use the old value
> 'item' as a dedicated pointer to point to the found element, which
> 1. can fix this bug, due to now 'item' is NULL only if it's not found.
> 2. do not need to change all the uses of 'item' after the loop.
> 3. can also limit the scope of the list iterator 'iter' *only inside*
>    the traversal loop by simply declaring 'iter' inside the loop in the
>    future, as usage of the iterator outside of the list_for_each_entry
>    is considered harmful. https://lkml.org/lkml/2022/2/17/1032
> 
> Fixes: a910e4a94f692 ("cw1200: add driver for the ST-E CW1100 & CW1200 WLAN chipsets")
> Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
> Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>

Failed to apply, please rebase on top of latest wireless-next.

Recorded preimage for 'drivers/net/wireless/st/cw1200/queue.c'
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Applying: cw1200: fix incorrect check to determine if no element is found in list
Using index info to reconstruct a base tree...
M	drivers/net/wireless/st/cw1200/queue.c
Falling back to patching base and 3-way merge...
Auto-merging drivers/net/wireless/st/cw1200/queue.c
CONFLICT (content): Merge conflict in drivers/net/wireless/st/cw1200/queue.c
Patch failed at 0001 cw1200: fix incorrect check to determine if no element is found in list

Patch set to Changes Requested.

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20220320035436.11293-1-xiam0nd.tong@gmail.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches