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From: "Manoharan, Rajkumar" <rmanohar@qti.qualcomm.com>
To: "greearb@candelatech.com" <greearb@candelatech.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH 2/3] ath10k: Grab rcu_read_lock before the txqs spinlock.
Date: Fri, 19 Aug 2016 03:01:14 +0000	[thread overview]
Message-ID: <1471575674214.65791@qti.qualcomm.com> (raw)
In-Reply-To: <1471569995-10028-2-git-send-email-greearb@candelatech.com>

> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
> index 916119c..d96c06e 100644
> --- a/drivers/net/wireless/ath/ath10k/mac.c
> +++ b/drivers/net/wireless/ath/ath10k/mac.c
> @@ -4307,8 +4307,8 @@ void ath10k_mac_tx_push_pending(struct ath10k *ar)
>         int max;
>         int loop_max = 2000;
> 
> -       spin_lock_bh(&ar->txqs_lock);
>         rcu_read_lock();
> +       spin_lock_bh(&ar->txqs_lock);
>
Ben,

It is quite possible that push_pending can be preempted after acquiring rcu_lock which
may lead to deadlock. no? I assume to prevent that spin_lock is taken first. 

Could you please explain how this reordering is fixing dead lock?

-Rajkumar
_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

WARNING: multiple messages have this Message-ID (diff)
From: "Manoharan, Rajkumar" <rmanohar@qti.qualcomm.com>
To: "greearb@candelatech.com" <greearb@candelatech.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH 2/3] ath10k:  Grab rcu_read_lock before the txqs spinlock.
Date: Fri, 19 Aug 2016 03:01:14 +0000	[thread overview]
Message-ID: <1471575674214.65791@qti.qualcomm.com> (raw)
In-Reply-To: <1471569995-10028-2-git-send-email-greearb@candelatech.com>

> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless=
/ath/ath10k/mac.c=0A=
> index 916119c..d96c06e 100644=0A=
> --- a/drivers/net/wireless/ath/ath10k/mac.c=0A=
> +++ b/drivers/net/wireless/ath/ath10k/mac.c=0A=
> @@ -4307,8 +4307,8 @@ void ath10k_mac_tx_push_pending(struct ath10k *ar)=
=0A=
>         int max;=0A=
>         int loop_max =3D 2000;=0A=
> =0A=
> -       spin_lock_bh(&ar->txqs_lock);=0A=
>         rcu_read_lock();=0A=
> +       spin_lock_bh(&ar->txqs_lock);=0A=
>=0A=
Ben,=0A=
=0A=
It is quite possible that push_pending can be preempted after acquiring rcu=
_lock which=0A=
may lead to deadlock. no? I assume to prevent that spin_lock is taken first=
. =0A=
=0A=
Could you please explain how this reordering is fixing dead lock?=0A=
=0A=
-Rajkumar=

  reply	other threads:[~2016-08-19  3:01 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-19  1:26 [PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries greearb
2016-08-19  1:26 ` greearb
2016-08-19  1:26 ` [PATCH 2/3] ath10k: Grab rcu_read_lock before the txqs spinlock greearb
2016-08-19  1:26   ` greearb
2016-08-19  3:01   ` Manoharan, Rajkumar [this message]
2016-08-19  3:01     ` Manoharan, Rajkumar
2016-08-19  3:28     ` Ben Greear
2016-08-19  3:28       ` Ben Greear
2016-09-09 13:36   ` Valo, Kalle
2016-09-09 13:36     ` Valo, Kalle
2016-09-09 14:47     ` Ben Greear
2016-09-09 14:47       ` Ben Greear
2016-09-12  6:41       ` Johannes Berg
2016-09-12  6:41         ` Johannes Berg
2016-09-12 16:37         ` Ben Greear
2016-09-12 16:37           ` Ben Greear
2016-08-19  1:26 ` [PATCH 3/3] ath10k: Improve logging message greearb
2016-08-19  1:26   ` greearb
2016-08-19  6:35   ` Mohammed Shafi Shajakhan
2016-08-19  6:35     ` Mohammed Shafi Shajakhan
2016-09-09 13:30     ` Valo, Kalle
2016-09-09 13:30       ` Valo, Kalle
2016-09-13 12:29   ` [3/3] " Kalle Valo
2016-09-13 12:29     ` Kalle Valo
2016-08-19  6:59 ` [PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries Michal Kazior
2016-08-19  6:59   ` Michal Kazior
2016-08-19 13:34   ` Ben Greear
2016-08-19 13:34     ` Ben Greear
2016-12-01 22:52     ` Ben Greear
2016-12-01 22:52       ` Ben Greear
2016-12-02  0:24       ` Ben Greear
2016-12-02  0:24         ` Ben Greear
2016-12-05  8:50         ` Michal Kazior
2016-12-05  8:50           ` Michal Kazior
2016-12-05 18:19           ` Ben Greear
2016-12-05 18:19             ` Ben Greear
2016-09-09 17:25 ` Felix Fietkau
2016-09-09 17:25   ` Felix Fietkau
2016-09-09 17:46   ` Ben Greear
2016-09-09 17:46     ` Ben Greear

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