On Friday, February 22, 2013 4:27 PM, Dmitry Torokhov wrote: > On Fri, Feb 22, 2013 at 04:12:36PM +0900, Jingoo Han wrote: > > On Friday, February 22, 2013 3:54 PM, Dmitry Torokhov wrote: > > > > > > Hi, > > > > > > It looks like a whole slew of devm_request_irq() conversions just got > > > applied to mainline and many of them are quite broken. > > > > > > Consider fd5231ce336e038037b4f0190a6838bdd6e17c6d or > > > c1879fe80c61f3be6f2ddb82509c2e7f92a484fe: the drivers udsed first to > > > free IRQ and then unregister the corresponding device ensuring that IRQ > > > handler, while it runs, has the device available. The mechanic > > > conversion to devm_request_irq() reverses the order of these operations > > > opening the race window where IRQ can reference device (or other > > > resource) that is already gone. > > > > > > It would be nice if these could be reverted and revioewed again for > > > correctness. > > > > Um, other RTC drivers already have been using devm_request_threaded_irq() or > > devm_request_irq() like this, before I added these patches. > > > > For example, > > ./drivers/rtc/rtc-tegra.c > > ./drivers/rtc/rtc-spear.c > > ./drivers/rtc/rtc-s3c.c > > ./drivers/rtc/rtc-mxc.c > > ./drivers/rtc/rtc-ds1553.c > > ./drivers/rtc/rtc-ds1511.c > > ./drivers/rtc/rtc-snvs.c > > ./drivers/rtc/rtc-imxdi.c > > ./drivers/rtc/rtc-tx4939.c > > ./drivers/rtc/rtc-mv.c > > ./drivers/rtc/rtc-coh901331.c > > ./drivers/rtc/rtc-stk17ta8.c > > ./drivers/rtc/rtc-lpc32xx.c > > ./drivers/rtc/rtc-tps65910.c > > ./drivers/rtc/rtc-rc5t583.c > > > > > > Also, even more, some RTC drivers calls rtc_device_unregister() first, > > then calls free_irq() later. > > > > For example, > > ./drivers/rtc/rtc-vr41xx.c > > ./drivers/rtc/rtc-da9052.c > > ./drivers/rtc/rtc-isl1208.c > > ./drivers/rtc/rtc-88pm860x.c > > ./drivers/rtc/rtc-tps6586x.c > > ./drivers/rtc/rtc-mpc5121.c > > ./drivers/rtc/rtc-m48t59.c > > > > > > Please, don't argue revert without concrete reasons. > > What more concrete reason do you need? I explained to you the exact > reason on the patches I noticed before and also on the 2 commits > referenced above: blind conversion to devm_* changes order of operation > which may be deadly with IRQs (but others, like clocks and regulators, > are important too). > > The fact that crap slipped in the kernel before is not the valid reason > for adding more of the same crap. > > Please *understand* APIs you are using before making changes. > > > > > If these devm_request_threaded_irq() or devm_request_irq() make the problem, > > devm_free_irq() will be added later. > > And the point? If you use devm_request_irq() and then call > devm_free_irq() manually in all paths what you achieved is waste of > memory required for devm_* tracking.
CC'ed Al Viro, Tejun Heo So, is there any report that the devm_request_threaded_irq() makes the deadly problem related IRQ in such cases? According to your comment, it seems that there is no reason to use devm_request_irq() or devm_request_threaded_irq(). Please, argue that it would be better to deprecate devm_request_irq() or devm_request_threaded_irq(). > > -- > Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
