From: Julia Lawall <julia.lawall@lip6.fr>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
kernel-janitors@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
linux-media@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
devel@driverdev.osuosl.org, Kristian Beilke <beilke@posteo.de>
Subject: Re: [PATCH v1 05/10] staging: atomisp: Remove non-ACPI leftovers
Date: Tue, 2 Jan 2018 11:36:05 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1801021135000.24055@hadrien> (raw)
In-Reply-To: <20180102102644.km2lb65ehesphso7@mwanda>
On Tue, 2 Jan 2018, Dan Carpenter wrote:
> On Wed, Dec 20, 2017 at 11:30:01AM +0100, Julia Lawall wrote:
> >
> >
> > On Wed, 20 Dec 2017, Dan Carpenter wrote:
> >
> > > On Tue, Dec 19, 2017 at 10:59:52PM +0200, Andy Shevchenko wrote:
> > > > @@ -914,9 +904,7 @@ static int lm3554_probe(struct i2c_client *client)
> > > > dev_err(&client->dev, "gpio request/direction_output fail");
> > > > goto fail2;
> > > > }
> > > > - if (ACPI_HANDLE(&client->dev))
> > > > - err = atomisp_register_i2c_module(&flash->sd, NULL, LED_FLASH);
> > > > - return 0;
> > > > + return atomisp_register_i2c_module(&flash->sd, NULL, LED_FLASH);
> > > > fail2:
> > > > media_entity_cleanup(&flash->sd.entity);
> > > > v4l2_ctrl_handler_free(&flash->ctrl_handler);
> > >
> > > Actually every place where we directly return a function call is wrong
> > > and needs error handling added. I've been meaning to write a Smatch
> > > check for this because it's a common anti-pattern we don't check the
> > > last function call for errors.
> > >
> > > Someone could probably do the same in Coccinelle if they want.
> >
> > I'm not sure what you are suggesting. Is every case of return f(...);
> > for any f wrong? Or is it a particular function that is of concern? Or
> > would it be that every function call that has error handling somewhere
> > should have error handling everywhere? Or is it related to what seems to
> > be the problem in the above code that err is initialized but nothing
> > happens to it?
> >
>
> I was just thinking that it's a common pattern to treat the last
> function call differently and one mistake I often see looks like this:
>
> ret = frob();
> if (ret) {
> cleanup();
> return ret;
> }
>
> return another_function();
>
> No error handling for the last function call.
OK, I see. When there was error handling code along the way, a direct
return of a function that could fail needs error handling code too.
Thanks for the clarification,
julia
WARNING: multiple messages have this Message-ID (diff)
From: Julia Lawall <julia.lawall@lip6.fr>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
kernel-janitors@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
linux-media@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
devel@driverdev.osuosl.org, Kristian Beilke <beilke@posteo.de>
Subject: Re: [PATCH v1 05/10] staging: atomisp: Remove non-ACPI leftovers
Date: Tue, 02 Jan 2018 10:36:05 +0000 [thread overview]
Message-ID: <alpine.DEB.2.20.1801021135000.24055@hadrien> (raw)
In-Reply-To: <20180102102644.km2lb65ehesphso7@mwanda>
On Tue, 2 Jan 2018, Dan Carpenter wrote:
> On Wed, Dec 20, 2017 at 11:30:01AM +0100, Julia Lawall wrote:
> >
> >
> > On Wed, 20 Dec 2017, Dan Carpenter wrote:
> >
> > > On Tue, Dec 19, 2017 at 10:59:52PM +0200, Andy Shevchenko wrote:
> > > > @@ -914,9 +904,7 @@ static int lm3554_probe(struct i2c_client *client)
> > > > dev_err(&client->dev, "gpio request/direction_output fail");
> > > > goto fail2;
> > > > }
> > > > - if (ACPI_HANDLE(&client->dev))
> > > > - err = atomisp_register_i2c_module(&flash->sd, NULL, LED_FLASH);
> > > > - return 0;
> > > > + return atomisp_register_i2c_module(&flash->sd, NULL, LED_FLASH);
> > > > fail2:
> > > > media_entity_cleanup(&flash->sd.entity);
> > > > v4l2_ctrl_handler_free(&flash->ctrl_handler);
> > >
> > > Actually every place where we directly return a function call is wrong
> > > and needs error handling added. I've been meaning to write a Smatch
> > > check for this because it's a common anti-pattern we don't check the
> > > last function call for errors.
> > >
> > > Someone could probably do the same in Coccinelle if they want.
> >
> > I'm not sure what you are suggesting. Is every case of return f(...);
> > for any f wrong? Or is it a particular function that is of concern? Or
> > would it be that every function call that has error handling somewhere
> > should have error handling everywhere? Or is it related to what seems to
> > be the problem in the above code that err is initialized but nothing
> > happens to it?
> >
>
> I was just thinking that it's a common pattern to treat the last
> function call differently and one mistake I often see looks like this:
>
> ret = frob();
> if (ret) {
> cleanup();
> return ret;
> }
>
> return another_function();
>
> No error handling for the last function call.
OK, I see. When there was error handling code along the way, a direct
return of a function that could fail needs error handling code too.
Thanks for the clarification,
julia
next prev parent reply other threads:[~2018-01-02 10:36 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-19 20:59 [PATCH v1 01/10] staging: atomisp: Don't leak GPIO resources if clk_get() failed Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 02/10] staging: atomisp: Remove duplicate NULL-check Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 03/10] staging: atomisp: lm3554: Fix control values Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 04/10] staging: atomisp: Disable custom format for now Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 05/10] staging: atomisp: Remove non-ACPI leftovers Andy Shevchenko
2017-12-20 4:54 ` Dan Carpenter
2017-12-20 10:24 ` Andy Shevchenko
2017-12-21 22:34 ` Sakari Ailus
2017-12-20 5:38 ` Dan Carpenter
2017-12-20 5:38 ` Dan Carpenter
2017-12-20 10:30 ` Julia Lawall
2017-12-20 10:30 ` Julia Lawall
2018-01-02 10:26 ` Dan Carpenter
2018-01-02 10:26 ` Dan Carpenter
2018-01-02 10:36 ` Julia Lawall [this message]
2018-01-02 10:36 ` Julia Lawall
2017-12-20 12:27 ` walter harms
2017-12-20 12:36 ` Julia Lawall
2017-12-19 20:59 ` [PATCH v1 06/10] staging: atomisp: Switch to use struct device_driver directly Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 07/10] staging: atomisp: Remove redundant PCI code Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 08/10] staging: atomisp: Unexport local function Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 09/10] staging: atomisp: Use standard DMI match table Andy Shevchenko
2017-12-19 20:59 ` [PATCH v1 10/10] staging: atomisp: Fix DMI matching entry for MRD7 Andy Shevchenko
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