Hi Johan, And thanks so much for this patch series. Johan Hovold <johan+linaro@xxxxxxxxxx> (2023-02-13): > Parallel probing of devices that share interrupts (e.g. when a driver > uses asynchronous probing) can currently result in two mappings for the > same hardware interrupt to be created due to missing serialisation. > > Make sure to hold the irq_domain_mutex when creating mappings so that > looking for an existing mapping before creating a new one is done > atomically. Just for information: This patch fixes a long-standing regression regarding Raspberry Pi devices, which have been failing to boot (at least reliably) due to MMC timeouts for a long while; I think that started between v5.17 and v5.19, but I couldn't bisect at the time (I was already chasing some other regression). Example bug report: https://bugs.debian.org/1019700 Before trying to pinpoint when the regression appeared, I've checked these versions, with a Debian testing userspace as of 2023-03-07: - v6.1.12: affected. - v6.2: affected. - v6.3-rc1: not affected. A bisect between v6.2 and v6.3-rc1 led me to this patch specifically. Seeing how it's part of a patch series, and how previous patches are preliminary ones, I've checked that cherry-picking the first 6 patches on top of v6.1.15 indeed fixes the problem there too, and it does (git cherry-pick v6.2-rc4..601363cc08da25747feb87c55573dd54de91d66a). With the following systems: - Pi 4 B, using external storage (SD card), - CM4 Lite on CM4 IO Board, using external storage (SD card), - CM4 on CM4 IO Board, using internal storage (eMMC), I've been able to verify that v6.1.12 (baseline in Debian testing) triggers this MMC timeout issue, while v6.1.15 + the aforementioned range of cherry-picked commits no longer triggers this issue. (Methodology: cold boot then reboot 20 times, monitoring via serial console to keep HDMI output of the equation; affected systems stop booting after 1-4 boots; unaffected systems boot and reboot just fine all the time.) This looks like a critical bugfix for Raspberry Pi users. Seeing the stable@ mention is about 4.8, I suppose this is going to be considered for a wide range of kernels already… but I'm happy to dig into this further to pinpoint when the regression appeared, if that's helpful. Cheers, -- Cyril Brulebois (kibi@xxxxxxxxxx) <https://debamax.com/> D-I release manager -- Release team member -- Freelance Consultant
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