linux-kernel - Re: [BUG] radio-gemtek-pci.c: double mutex

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Date:	Thu, 8 Oct 2009 20:47:25 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Alexander Strakh <strakh@...ras.ru>
Cc:	Vladimir Shebordaev <vshebordaev@...l.ru>,
	Mauro Carvalho Chehab <mchehab@...radead.org>,
	linux-media@...r.kernel.org,
	Linux Kernlel Mailing List <linux-kernel@...r.kernel.org>,
	Hans Verkuil <hverkuil@...all.nl>
Subject: Re: [BUG] radio-gemtek-pci.c: double mutex_lock

On Thu, 8 Oct 2009, Alexander Strakh wrote:

> 	KERNEL_VERSION: 2.6.31
> 	DESCRIBE:
> In driver ./drivers/media/radio/radio-gemtek-pci.c 
> mutex_lock is called first time in line 184, then in line 186 
> gemtek_pci_setfrequency is called.
> 
> 182 static void gemtek_pci_unmute(struct gemtek_pci *card)
> 183 {
> 184		mutex_lock(&card->lock);
> 185		if (card->mute) {
> 186         	gemtek_pci_setfrequency(card, card->current_frequency);
> 187			card->mute = false;
> 188		}
> 189		mutex_unlock(&card->lock);190 }
> 
> In gemtek_pci_setfrequency we call mutex_lock again in line 152
> 
> 144 static void gemtek_pci_setfrequency(struct gemtek_pci *card, unsigned long 
> frequency)
> 145 {
> 146         int i;
> 147         u32 value = frequency / 200 + 856;
> 148         u16 mask = 0x8000;
> 149         u8 last_byte;
> 150         u32 port = card->iobase;
> 151
> 152         mutex_lock(&card->lock);

Good catch. Adding Hans, who added the (incorrect) locking into 
gemtek_pci_unmute(), to CC.

-- 
Jiri Kosina
SUSE Labs, Novell Inc.

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