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Date: Thu, 22 Jun 2017 22:08:56 +0200 From: Michał Kępień <kernel@...pniu.pl> To: Darren Hart <dvhart@...radead.org> Cc: Rafael Wysocki <rjw@...ysocki.net>, Jonathan Woithe <jwoithe@...t42.net>, Andy Shevchenko <andy@...radead.org>, platform-driver-x86@...r.kernel.org, linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/7] platform/x86: fujitsu-laptop: do not use kfifo for storing hotkey scancodes > On Fri, Jun 16, 2017 at 06:40:52AM +0200, Michał Kępień wrote: > > All ACPI device notify callbacks are invoked using acpi_os_execute(), > > which causes the supplied callback to be queued to a static workqueue > > which always executes on CPU 0. This means that there is no possibility > > for any ACPI device notify callback to be concurrently executed on > > multiple CPUs, which in the case of fujitsu-laptop means that using a > > locked kfifo for handling hotkeys is redundant: as hotkey scancodes are > > only pushed and popped from within acpi_fujitsu_laptop_notify(), no risk > > of concurrent pushing and popping exists. > > Was the kfifo causing a problem currently or for the migration to separate > modules? Is this purely a simplification? It is just another step in stripping fujitsu-laptop down to its bare essentials. If my reasoning quoted above is correct, using a locked kfifo needlessly suggests potential concurrency issues, but it is definitely not an error. -- Best regards, Michał Kępień
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