Hi all I am uncertain about the correct mmc host clean up order, namely what should happen first: interrupt handlers freed or mmc_remove_host() called? First freeing interrupts doesn't seem to be a good idea. mmc_remove_host() can be waiting for interrupts, which then deadlocks. So, interrupts must be freed after mmc_remove_host(). But that creates a window, during which if an interrupt occurs, bad things can happen(TM). But normal MMC interrupts are not supposed to happen after mmc_remove_host() returns - no more requests will be flying. But there are two more kinds of interrupts, that still can happen in that window: hotplug and SDIO. To prevent hotplug, e.g., the sdhci driver, calls sdhci_disable_card_detection(). That helps against that race, but - what if we then miss a card eject between that call and mmc_remove_host()? Won't the core then try to communicate with a card, that's gone? And then SDIO. We could do a similar thing - prohibit processing of SDIO interrupts before calling mmc_remove_host(). But could it be the case, that a higher level kernel driver is waiting for that SDIO interrupt, and then mmc_remove_host() will be waiting for that driver to release the card (if anything like that is happening in mmc?), and they will deadlock? Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
