* [PATCH] USB: core: Improve unlocking of a mutex in two functions
@ 2017-11-04 20:12 SF Markus Elfring
2017-11-04 23:25 ` Geert Uytterhoeven
0 siblings, 1 reply; 5+ messages in thread
From: SF Markus Elfring @ 2017-11-04 20:12 UTC (permalink / raw)
To: linux-usb, Alan Stern, Eugene Korenevsky, Geert Uytterhoeven,
Greg Kroah-Hartman, Günter Röck, Jaejoong Kim,
Johan Hovold, Jonathan Corbet, Mathias Nyman,
Mauro Carvalho Chehab
Cc: LKML, kernel-janitors
From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sat, 4 Nov 2017 21:00:46 +0100
* Add jump targets so that a call of the function "mutex_unlock" is stored
only twice in these function implementations.
* Replace five calls by goto statements.
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
drivers/usb/core/hub.c | 8 ++++----
drivers/usb/core/message.c | 18 ++++++++++--------
2 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 196a0a5540ed..8f3067c2015c 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -5518,8 +5518,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
dev_warn(&udev->dev,
"Busted HC? Not enough HCD resources for "
"old configuration.\n");
- mutex_unlock(hcd->bandwidth_mutex);
- goto re_enumerate;
+ goto unlock;
}
ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
USB_REQ_SET_CONFIGURATION, 0,
@@ -5529,8 +5528,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
dev_err(&udev->dev,
"can't restore configuration #%d (error=%d)\n",
udev->actconfig->desc.bConfigurationValue, ret);
- mutex_unlock(hcd->bandwidth_mutex);
- goto re_enumerate;
+ goto unlock;
}
mutex_unlock(hcd->bandwidth_mutex);
usb_set_device_state(udev, USB_STATE_CONFIGURED);
@@ -5583,6 +5581,8 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
udev->bos = bos;
return 0;
+unlock:
+ mutex_unlock(hcd->bandwidth_mutex);
re_enumerate:
usb_release_bos_descriptor(udev);
udev->bos = bos;
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 371a07d874a3..fe8e36cc7def 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1321,8 +1321,8 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
*/
if (usb_disable_lpm(dev)) {
dev_err(&iface->dev, "%s Failed to disable LPM\n.", __func__);
- mutex_unlock(hcd->bandwidth_mutex);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto unlock;
}
/* Changing alt-setting also frees any allocated streams */
for (i = 0; i < iface->cur_altsetting->desc.bNumEndpoints; i++)
@@ -1332,9 +1332,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
if (ret < 0) {
dev_info(&dev->dev, "Not enough bandwidth for altsetting %d\n",
alternate);
- usb_enable_lpm(dev);
- mutex_unlock(hcd->bandwidth_mutex);
- return ret;
+ goto enable_lpm;
}
if (dev->quirks & USB_QUIRK_NO_SET_INTF)
@@ -1355,9 +1353,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
} else if (ret < 0) {
/* Re-instate the old alt setting */
usb_hcd_alloc_bandwidth(dev, NULL, alt, iface->cur_altsetting);
- usb_enable_lpm(dev);
- mutex_unlock(hcd->bandwidth_mutex);
- return ret;
+ goto enable_lpm;
}
mutex_unlock(hcd->bandwidth_mutex);
@@ -1413,6 +1409,12 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
create_intf_ep_devs(iface);
}
return 0;
+
+enable_lpm:
+ usb_enable_lpm(dev);
+unlock:
+ mutex_unlock(hcd->bandwidth_mutex);
+ return ret;
}
EXPORT_SYMBOL_GPL(usb_set_interface);
--
2.15.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] USB: core: Improve unlocking of a mutex in two functions
2017-11-04 20:12 [PATCH] USB: core: Improve unlocking of a mutex in two functions SF Markus Elfring
@ 2017-11-04 23:25 ` Geert Uytterhoeven
2017-11-05 7:30 ` Greg Kroah-Hartman
2017-11-05 8:29 ` [PATCH] " SF Markus Elfring
0 siblings, 2 replies; 5+ messages in thread
From: Geert Uytterhoeven @ 2017-11-04 23:25 UTC (permalink / raw)
To: SF Markus Elfring
Cc: USB list, Alan Stern, Eugene Korenevsky, Greg Kroah-Hartman,
Günter Röck, Jaejoong Kim, Johan Hovold,
Jonathan Corbet, Mathias Nyman, Mauro Carvalho Chehab, LKML,
kernel-janitors@vger.kernel.org
On Sat, Nov 4, 2017 at 9:12 PM, SF Markus Elfring
<elfring@users.sourceforge.net> wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sat, 4 Nov 2017 21:00:46 +0100
>
> * Add jump targets so that a call of the function "mutex_unlock" is stored
> only twice in these function implementations.
>
> * Replace five calls by goto statements.
>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
NAKed-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> drivers/usb/core/hub.c | 8 ++++----
> drivers/usb/core/message.c | 18 ++++++++++--------
> 2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 196a0a5540ed..8f3067c2015c 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -5518,8 +5518,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
> dev_warn(&udev->dev,
> "Busted HC? Not enough HCD resources for "
> "old configuration.\n");
> - mutex_unlock(hcd->bandwidth_mutex);
> - goto re_enumerate;
> + goto unlock;
> }
> ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
> USB_REQ_SET_CONFIGURATION, 0,
> @@ -5529,8 +5528,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
> dev_err(&udev->dev,
> "can't restore configuration #%d (error=%d)\n",
> udev->actconfig->desc.bConfigurationValue, ret);
> - mutex_unlock(hcd->bandwidth_mutex);
> - goto re_enumerate;
> + goto unlock;
> }
> mutex_unlock(hcd->bandwidth_mutex);
> usb_set_device_state(udev, USB_STATE_CONFIGURED);
> @@ -5583,6 +5581,8 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
> udev->bos = bos;
> return 0;
>
> +unlock:
> + mutex_unlock(hcd->bandwidth_mutex);
This makes it harder for the reader, as the mutex_unlock() is now far
below the block
of code that's protected by the lock.
> re_enumerate:
> usb_release_bos_descriptor(udev);
> udev->bos = bos;
> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> index 371a07d874a3..fe8e36cc7def 100644
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -1321,8 +1321,8 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
> */
> if (usb_disable_lpm(dev)) {
> dev_err(&iface->dev, "%s Failed to disable LPM\n.", __func__);
> - mutex_unlock(hcd->bandwidth_mutex);
> - return -ENOMEM;
> + ret = -ENOMEM;
> + goto unlock;
> }
> /* Changing alt-setting also frees any allocated streams */
> for (i = 0; i < iface->cur_altsetting->desc.bNumEndpoints; i++)
> @@ -1332,9 +1332,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
> if (ret < 0) {
> dev_info(&dev->dev, "Not enough bandwidth for altsetting %d\n",
> alternate);
> - usb_enable_lpm(dev);
> - mutex_unlock(hcd->bandwidth_mutex);
> - return ret;
> + goto enable_lpm;
> }
>
> if (dev->quirks & USB_QUIRK_NO_SET_INTF)
> @@ -1355,9 +1353,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
> } else if (ret < 0) {
> /* Re-instate the old alt setting */
> usb_hcd_alloc_bandwidth(dev, NULL, alt, iface->cur_altsetting);
> - usb_enable_lpm(dev);
> - mutex_unlock(hcd->bandwidth_mutex);
> - return ret;
> + goto enable_lpm;
> }
> mutex_unlock(hcd->bandwidth_mutex);
>
> @@ -1413,6 +1409,12 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
> create_intf_ep_devs(iface);
> }
> return 0;
> +
> +enable_lpm:
> + usb_enable_lpm(dev);
> +unlock:
> + mutex_unlock(hcd->bandwidth_mutex);
Likewise.
> + return ret;
> }
> EXPORT_SYMBOL_GPL(usb_set_interface);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] USB: core: Improve unlocking of a mutex in two functions
2017-11-04 23:25 ` Geert Uytterhoeven
@ 2017-11-05 7:30 ` Greg Kroah-Hartman
2017-11-05 9:33 ` SF Markus Elfring
2017-11-05 8:29 ` [PATCH] " SF Markus Elfring
1 sibling, 1 reply; 5+ messages in thread
From: Greg Kroah-Hartman @ 2017-11-05 7:30 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: SF Markus Elfring, USB list, Alan Stern, Eugene Korenevsky,
Günter Röck, Jaejoong Kim, Johan Hovold,
Jonathan Corbet, Mathias Nyman, Mauro Carvalho Chehab, LKML,
kernel-janitors@vger.kernel.org
On Sun, Nov 05, 2017 at 12:25:19AM +0100, Geert Uytterhoeven wrote:
> On Sat, Nov 4, 2017 at 9:12 PM, SF Markus Elfring
> <elfring@users.sourceforge.net> wrote:
> > From: Markus Elfring <elfring@users.sourceforge.net>
> > Date: Sat, 4 Nov 2017 21:00:46 +0100
> >
> > * Add jump targets so that a call of the function "mutex_unlock" is stored
> > only twice in these function implementations.
> >
> > * Replace five calls by goto statements.
> >
> > This issue was detected by using the Coccinelle software.
> >
> > Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
>
> NAKed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Don't worry, or waste your time, I don't take patches from this author
as they are in my blacklist.
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: USB: core: Improve unlocking of a mutex in two functions
2017-11-05 7:30 ` Greg Kroah-Hartman
@ 2017-11-05 9:33 ` SF Markus Elfring
0 siblings, 0 replies; 5+ messages in thread
From: SF Markus Elfring @ 2017-11-05 9:33 UTC (permalink / raw)
To: Greg Kroah-Hartman, linux-usb, kernel-janitors
Cc: Geert Uytterhoeven, Alan Stern, Eugene Korenevsky,
Günter Röck, Jaejoong Kim, Johan Hovold,
Jonathan Corbet, Mathias Nyman, Mauro Carvalho Chehab, LKML
> Don't worry, or waste your time, I don't take patches from this author
> as they are in my blacklist.
I am curious if our dialogue can become more constructive again. 🌈
I can offer another bit of information for this software development discussion. 💭
The affected source files can be compiled for the processor architecture “x86_64”
by a tool like “GCC 6.4.1+r251631-1.3” from the software distribution
“openSUSE Tumbleweed” with the following command example.
my_cc=/usr/bin/gcc-6 \
&& my_module1=drivers/usb/core/hub.o \
&& my_module2=drivers/usb/core/message.o \
&& git checkout next-20171102 \
&& make -j4 CC="${my_cc}" HOSTCC="${my_cc}" allmodconfig "${my_module1}" "${my_module2}" \
&& size "${my_module1}" "${my_module2}" \
&& git checkout ':/^USB: core: Improve unlocking of a mutex in two functions' \
&& make -j4 CC="${my_cc}" HOSTCC="${my_cc}" allmodconfig "${my_module1}" "${my_module2}" \
&& size "${my_module1}" "${my_module2}"
🔮 Do you find the following differences useful for further clarification?
╔═════════╤══════╗
║ module │ text ║
╠═════════╪══════╣
║ hub │ -16 ║
║ message │ -48 ║
╚═════════╧══════╝
Regards,
Markus
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] USB: core: Improve unlocking of a mutex in two functions
2017-11-04 23:25 ` Geert Uytterhoeven
2017-11-05 7:30 ` Greg Kroah-Hartman
@ 2017-11-05 8:29 ` SF Markus Elfring
1 sibling, 0 replies; 5+ messages in thread
From: SF Markus Elfring @ 2017-11-05 8:29 UTC (permalink / raw)
To: Geert Uytterhoeven, linux-usb, kernel-janitors
Cc: Alan Stern, Eugene Korenevsky, Greg Kroah-Hartman,
Günter Röck, Jaejoong Kim, Johan Hovold,
Jonathan Corbet, Mathias Nyman, Mauro Carvalho Chehab, LKML
>> @@ -5529,8 +5528,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
>> dev_err(&udev->dev,
>> "can't restore configuration #%d (error=%d)\n",
>> udev->actconfig->desc.bConfigurationValue, ret);
>> - mutex_unlock(hcd->bandwidth_mutex);
>> - goto re_enumerate;
>> + goto unlock;
>> }
>> mutex_unlock(hcd->bandwidth_mutex);
>> usb_set_device_state(udev, USB_STATE_CONFIGURED);
>> @@ -5583,6 +5581,8 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
>> udev->bos = bos;
>> return 0;
>>
>> +unlock:
>> + mutex_unlock(hcd->bandwidth_mutex);
>
> This makes it harder for the reader,
I am curious if the view on the preferred code readability can be clarified further.
> as the mutex_unlock() is now far below the block
> of code that's protected by the lock.
I got an other software development opinion for this aspect.
Can the label be clear enough about the shown purpose already?
Regards,
Markus
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-11-05 9:34 UTC | newest]
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2017-11-04 20:12 [PATCH] USB: core: Improve unlocking of a mutex in two functions SF Markus Elfring
2017-11-04 23:25 ` Geert Uytterhoeven
2017-11-05 7:30 ` Greg Kroah-Hartman
2017-11-05 9:33 ` SF Markus Elfring
2017-11-05 8:29 ` [PATCH] " SF Markus Elfring
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