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Groups > linux.kernel > #1370323
| From | Rich Felker <dalias@libc.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | 4.6-rc1 regression in SPI core -- deadlock |
| Date | 2016-04-04 03:30 +0200 |
| Message-ID | <rk1v4-3Ki-3@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
I've spent several days trying to debug a deadlock using our local (not yet ready for upstream) driver for the J-Core SPI device and it seems to be a new deadlock in the SPI core caused by commit 556351f14e74 and unrelated to the particular driver. Commit 49023d2e4ead tried to solve a related deadlock problem, but there still seems to be a lock order issue and it's affecting SPI use even without the spi_flash_read optimization. The deadlock I'm observing has a kworker thread stuck in wait_for_completion called from spi_sync_locked (ultimately from mmc_rescan) and the completion is never finishing because this kworker thread has the bus locked while the spi master task has already started processing the queue but can't proceed because the bus lock is taken. Anyone else seen this? Ideas for a proper fix? I've got it working for me by disabling the bus locking in __spi_pump_messages entirely (like before commit 556351f14e74) but I'm pretty sure this breaks the new feature that was added. Rich
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4.6-rc1 regression in SPI core -- deadlock Rich Felker <dalias@libc.org> - 2016-04-04 03:30 +0200
Re: 4.6-rc1 regression in SPI core -- deadlock Vignesh R <vigneshr@ti.com> - 2016-04-04 06:00 +0200
Re: 4.6-rc1 regression in SPI core -- deadlock Rich Felker <dalias@libc.org> - 2016-04-04 09:10 +0200
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