• Linus Torvalds's avatar
    async: Fix module loading async-work regression · d6de2c80
    Linus Torvalds authored
    Several drivers use asynchronous work to do device discovery, and we
    synchronize with them in the compiled-in case before we actually try to
    mount root filesystems etc.
    However, when compiled as modules, that synchronization is missing - the
    module loading completes, but the driver hasn't actually finished
    probing for devices, and that means that any user mode that expects to
    use the devices after the 'insmod' is now potentially broken.
    We already saw one case of a similar issue in the ACPI battery code,
    where the kernel itself expected the module to be all done, and unmapped
    the init memory - but the async device discovery was still running.
    That got hacked around by just removing the "__init" (see commit
    5d38258e "ACPI battery: fix async boot
    oops"), but the real fix is to just make the module loading wait for all
    async work to be completed.
    It will slow down module loading, but since common devices should be
    built in anyway, and since the bug is really annoying and hard to handle
    from user space (and caused several S3 resume regressions), the simple
    fix to wait is the right one.
    This fixes at least
    but probably a few other bugzilla entries too (12936, for example), and
    is confirmed to fix Rafael's storage driver breakage after resume bug
    report (no bugzilla entry).
    We should also be able to now revert that ACPI battery fix.
    Reported-and-tested-by: default avatarRafael J. Wysocki <rjw@suse.com>
    Tested-by: default avatarHeinz Diehl <htd@fancy-poultry.org>
    Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
module.c 74.4 KB