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[RESEND,1/2] pinctrl: st: avoid multiple mutex lock

Message ID 1420452254-30625-2-git-send-email-patrice.chotard@st.com (mailing list archive)
State New, archived
Headers show

Commit Message

Patrice CHOTARD Jan. 5, 2015, 10:04 a.m. UTC 
From: Francesco VIRLINZI <francesco.virlinzi@st.com>

Using the sysfs inteface to inspect the pins configuration
the system can walk around a path which acquires the same
mutex twice.

On STiH407 platform, for example :
cat /sys/kernel/debug/pinctrl/920f080.pin-controller-front0/pinconf-pins
hangs the kernel and never returns.

With this patch the mutex is temporary freed.

Signed-off-by: Francesco Virlinzi <francesco.virlinzi@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
---
 drivers/pinctrl/pinctrl-st.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Linus Walleij Jan. 7, 2015, 9:44 a.m. UTC | #1 
On Mon, Jan 5, 2015 at 11:04 AM, Patrice CHOTARD <patrice.chotard@st.com> wrote:

> From: Francesco VIRLINZI <francesco.virlinzi@st.com>
>
> Using the sysfs inteface to inspect the pins configuration
> the system can walk around a path which acquires the same
> mutex twice.
>
> On STiH407 platform, for example :
> cat /sys/kernel/debug/pinctrl/920f080.pin-controller-front0/pinconf-pins
> hangs the kernel and never returns.
>
> With this patch the mutex is temporary freed.
>
> Signed-off-by: Francesco Virlinzi <francesco.virlinzi@st.com>
> Signed-off-by: Patrice Chotard <patrice.chotard@st.com>

Patch applied to fixes. Sorry for the delay.

Yours,
Linus Walleij
Patrice CHOTARD Jan. 7, 2015, 10:30 a.m. UTC | #2 
Hi Linus
On 01/07/2015 10:44 AM, Linus Walleij wrote:
> On Mon, Jan 5, 2015 at 11:04 AM, Patrice CHOTARD <patrice.chotard@st.com> wrote:
>
>> From: Francesco VIRLINZI <francesco.virlinzi@st.com>
>>
>> Using the sysfs inteface to inspect the pins configuration
>> the system can walk around a path which acquires the same
>> mutex twice.
>>
>> On STiH407 platform, for example :
>> cat /sys/kernel/debug/pinctrl/920f080.pin-controller-front0/pinconf-pins
>> hangs the kernel and never returns.
>>
>> With this patch the mutex is temporary freed.
>>
>> Signed-off-by: Francesco Virlinzi <francesco.virlinzi@st.com>
>> Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
> Patch applied to fixes. Sorry for the delay.

Don't worry ;-)

Thanks

>
> Yours,
> Linus Walleij
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Patch

diff --git a/drivers/pinctrl/pinctrl-st.c b/drivers/pinctrl/pinctrl-st.c
index 7c9d513..87570e6 100644
--- a/drivers/pinctrl/pinctrl-st.c
+++ b/drivers/pinctrl/pinctrl-st.c
@@ -1012,8 +1012,10 @@  static void st_pinconf_dbg_show(struct pinctrl_dev *pctldev,
 				   struct seq_file *s, unsigned pin_id)
 {
 	unsigned long config;
-	st_pinconf_get(pctldev, pin_id, &config);
 
+	mutex_unlock(&pctldev->mutex);
+	st_pinconf_get(pctldev, pin_id, &config);
+	mutex_lock(&pctldev->mutex);
 	seq_printf(s, "[OE:%ld,PU:%ld,OD:%ld]\n"
 		"\t\t[retime:%ld,invclk:%ld,clknotdat:%ld,"
 		"de:%ld,rt-clk:%ld,rt-delay:%ld]",