Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote: >On Wed, Sep 18, 2013 at 10:39:42AM +0100, Jonathan Cameron wrote: >> >> >> "Zubair Lutfullah :" <zubair.lutfullah@xxxxxxxxx> wrote: >> >On Tue, Sep 17, 2013 at 09:27:27PM -0700, Dmitry Torokhov wrote: >> >> Hi Zubair, >> >> >> >> On Tue, Sep 17, 2013 at 09:44:07AM +0500, Zubair Lutfullah wrote: >> >> > + >> >> > + ret = devm_request_threaded_irq(indio_dev->dev.parent, >> >> > + irq, >> >> > + pollfunc_th, pollfunc_bh, >> >> > + flags, indio_dev->name, >> >> > + indio_dev); >> >> > + if (ret) >> >> > + goto error_kfifo_free; >> >> > + >> >> > + indio_dev->setup_ops = setup_ops; >> >> > + indio_dev->modes |= INDIO_BUFFER_HARDWARE; >> >> > + >> >> > + ret = iio_buffer_register(indio_dev, >> >> > + indio_dev->channels, >> >> > + indio_dev->num_channels); >> >> > + if (ret) >> >> > + goto error_free_irq; >> >> > + >> >> > + return 0; >> >> > + >> >> > +error_free_irq: >> >> > + devm_free_irq(indio_dev->dev.parent, irq, indio_dev); >> >> >> >> What is the point of using devm_* here if you are doing explicit >> >> management of the resource anyway (you explicitly release it in >all >> >code >> >> paths)? >> >> >> >> Thanks. >> >> >> >> -- >> >> Dmitry >> > >> >I admit I am unaware at the moment about how it works. >> > >> >I use devm and simply ignore the error path? >> > >> >The devm function header description said something about using >> >devm_free when freeing. And this is the way I am used to seeing >> >error handling. >> > >> The devm interfaces ensure this is all cleaned when the device is >> removed thus avoiding the need to free the stuff explicitly. Device >> will get freed on deliberate remove and on an error from probe. Hence >> you can drop all calls to devm free. The devm free functions are only >> needed if you wish to free in order to reallocate. This might happen >> if you want to change a buffer size for instance. > >However in this case such conversion us dangerous. With all but IRQ >resource managed by the traditional methods they will be released first >with IRQ handler deregistered very last. Therefore if device is not >properly quiesced IRQ raised during driver unbinding is likely to >result >in kernel oops. > >IOW devm_request_irq() is very often evil (it is still useful if _all_ >your resources are managed by devm_*). > >In case of your driver I'd recommend switching to >request_irq()/free_irq() instead. > >Thanks. Pretty much all resources are devm managed in here https://git.kernel.org/cgit/linux/kernel/git/jic23/iio.git/tree/drivers/iio/adc/ti_am335x_adc.c?h=togreg&id=7a1aeba7ed0d5a1e83fd5a8ee2a2869430d40347 There is a left over calloc which could be converted but that's it. -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
