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From: Kalle Valo <kvalo@codeaurora.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Peter Oh <peter.oh@eero.com>,
	kernel-janitors@vger.kernel.org,
	Carl Huang <cjhuang@codeaurora.org>,
	linux-wireless@vger.kernel.org, ath11k@lists.infradead.org
Subject: Re: [PATCH v2] ath11k: fix a locking bug in ath11k_mac_op_start()
Date: Tue, 09 Feb 2021 09:47:10 +0200	[thread overview]
Message-ID: <87ft25vg1t.fsf@codeaurora.org> (raw)
In-Reply-To: <YBk4GoeE+yc0wlJH@mwanda> (Dan Carpenter's message of "Tue, 2 Feb 2021 14:31:38 +0300")

Dan Carpenter <dan.carpenter@oracle.com> writes:

> This error path leads to a Smatch warning:
>
> 	drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start()
> 	error: double unlocked '&ar->conf_mutex' (orig line 4251)
>
> We're not holding the lock when we do the "goto err;" so it leads to a
> double unlock.  The fix is to hold the lock for a little longer.
>
> Fixes: c83c500b55b6 ("ath11k: enable idle power save mode")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: reviewers were concern that v1 was racy
>
>  drivers/net/wireless/ath/ath11k/mac.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index c1608f64ea95..464d3425488b 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -4248,8 +4248,6 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>  	/* Configure the hash seed for hash based reo dest ring selection */
>  	ath11k_wmi_pdev_lro_cfg(ar, ar->pdev->pdev_id);
>  
> -	mutex_unlock(&ar->conf_mutex);
> -
>  	rcu_assign_pointer(ab->pdevs_active[ar->pdev_idx],
>  			   &ab->pdevs[ar->pdev_idx]);
>  
> @@ -4262,6 +4260,9 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>  			goto err;
>  		}
>  	}
> +
> +	mutex_unlock(&ar->conf_mutex);
> +
>  	return 0;
>  
>  err:
> -- 
> 2.30.0

But now rcu_assign_pointer() is called while conf_mutex is held,
previously it was not. I didn't check if this creates problems, but just
to be on the safe side I modified your patch to keep the original
functionality. Please check my changes in the pending branch:

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=8eff3667c211072a2107271139b81cbf8c7fd10a

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

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

WARNING: multiple messages have this Message-ID (diff)
From: Kalle Valo <kvalo@codeaurora.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: linux-wireless@vger.kernel.org, kernel-janitors@vger.kernel.org,
	Carl Huang <cjhuang@codeaurora.org>, Peter Oh <peter.oh@eero.com>,
	ath11k@lists.infradead.org
Subject: Re: [PATCH v2] ath11k: fix a locking bug in ath11k_mac_op_start()
Date: Tue, 09 Feb 2021 07:47:10 +0000	[thread overview]
Message-ID: <87ft25vg1t.fsf@codeaurora.org> (raw)
In-Reply-To: <YBk4GoeE+yc0wlJH@mwanda> (Dan Carpenter's message of "Tue, 2 Feb 2021 14:31:38 +0300")

Dan Carpenter <dan.carpenter@oracle.com> writes:

> This error path leads to a Smatch warning:
>
> 	drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start()
> 	error: double unlocked '&ar->conf_mutex' (orig line 4251)
>
> We're not holding the lock when we do the "goto err;" so it leads to a
> double unlock.  The fix is to hold the lock for a little longer.
>
> Fixes: c83c500b55b6 ("ath11k: enable idle power save mode")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: reviewers were concern that v1 was racy
>
>  drivers/net/wireless/ath/ath11k/mac.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index c1608f64ea95..464d3425488b 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -4248,8 +4248,6 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>  	/* Configure the hash seed for hash based reo dest ring selection */
>  	ath11k_wmi_pdev_lro_cfg(ar, ar->pdev->pdev_id);
>  
> -	mutex_unlock(&ar->conf_mutex);
> -
>  	rcu_assign_pointer(ab->pdevs_active[ar->pdev_idx],
>  			   &ab->pdevs[ar->pdev_idx]);
>  
> @@ -4262,6 +4260,9 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>  			goto err;
>  		}
>  	}
> +
> +	mutex_unlock(&ar->conf_mutex);
> +
>  	return 0;
>  
>  err:
> -- 
> 2.30.0

But now rcu_assign_pointer() is called while conf_mutex is held,
previously it was not. I didn't check if this creates problems, but just
to be on the safe side I modified your patch to keep the original
functionality. Please check my changes in the pending branch:

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&idŽff3667c211072a2107271139b81cbf8c7fd10a

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

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

WARNING: multiple messages have this Message-ID (diff)
From: Kalle Valo <kvalo@codeaurora.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: linux-wireless@vger.kernel.org, kernel-janitors@vger.kernel.org,
	Carl Huang <cjhuang@codeaurora.org>, Peter Oh <peter.oh@eero.com>,
	ath11k@lists.infradead.org
Subject: Re: [PATCH v2] ath11k: fix a locking bug in ath11k_mac_op_start()
Date: Tue, 09 Feb 2021 09:47:10 +0200	[thread overview]
Message-ID: <87ft25vg1t.fsf@codeaurora.org> (raw)
In-Reply-To: <YBk4GoeE+yc0wlJH@mwanda> (Dan Carpenter's message of "Tue, 2 Feb 2021 14:31:38 +0300")

Dan Carpenter <dan.carpenter@oracle.com> writes:

> This error path leads to a Smatch warning:
>
> 	drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start()
> 	error: double unlocked '&ar->conf_mutex' (orig line 4251)
>
> We're not holding the lock when we do the "goto err;" so it leads to a
> double unlock.  The fix is to hold the lock for a little longer.
>
> Fixes: c83c500b55b6 ("ath11k: enable idle power save mode")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: reviewers were concern that v1 was racy
>
>  drivers/net/wireless/ath/ath11k/mac.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index c1608f64ea95..464d3425488b 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -4248,8 +4248,6 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>  	/* Configure the hash seed for hash based reo dest ring selection */
>  	ath11k_wmi_pdev_lro_cfg(ar, ar->pdev->pdev_id);
>  
> -	mutex_unlock(&ar->conf_mutex);
> -
>  	rcu_assign_pointer(ab->pdevs_active[ar->pdev_idx],
>  			   &ab->pdevs[ar->pdev_idx]);
>  
> @@ -4262,6 +4260,9 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw)
>  			goto err;
>  		}
>  	}
> +
> +	mutex_unlock(&ar->conf_mutex);
> +
>  	return 0;
>  
>  err:
> -- 
> 2.30.0

But now rcu_assign_pointer() is called while conf_mutex is held,
previously it was not. I didn't check if this creates problems, but just
to be on the safe side I modified your patch to keep the original
functionality. Please check my changes in the pending branch:

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=8eff3667c211072a2107271139b81cbf8c7fd10a

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

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

-- 
ath11k mailing list
ath11k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath11k

  reply	other threads:[~2021-02-09  7:48 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02 11:31 [PATCH v2] ath11k: fix a locking bug in ath11k_mac_op_start() Dan Carpenter
2021-02-02 11:31 ` Dan Carpenter
2021-02-02 11:31 ` Dan Carpenter
2021-02-09  7:47 ` Kalle Valo [this message]
2021-02-09  7:47   ` Kalle Valo
2021-02-09  7:47   ` Kalle Valo
2021-02-09  8:10   ` Dan Carpenter
2021-02-09  8:10     ` Dan Carpenter
2021-02-09  8:10     ` Dan Carpenter
2021-02-10  7:46 ` Kalle Valo
2021-02-10  7:46 ` Kalle Valo
2021-02-10  7:46   ` Kalle Valo

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