From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> commit b292b50b0efcc7095d8bf15505fba6909bb35dce upstream. syzbot is reporting hung task in wait_for_device_probe() [1]. At least, we always need to decrement probe_count if we incremented probe_count in really_probe(). However, since I can't find "Resources present before probing" message in the console log, both "this message simply flowed off" and "syzbot is not hitting this path" will be possible. Therefore, while we are at it, let's also prepare for concurrent wait_for_device_probe() calls by replacing wake_up() with wake_up_all(). [1] https://syzkaller.appspot.com/bug?id=25c833f1983c9c1d512f4ff860dd0d7f5a2e2c0f Reported-by: syzbot <syzbot+805f5f6ae37411f15b64@xxxxxxxxxxxxxxxxxxxxxxxxx> Fixes: 7c35e699c88bd607 ("driver core: Print device when resources present in really_probe()") Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: stable <stable@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200713021254.3444-1-penguin-kernel@xxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/base/dd.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -276,7 +276,7 @@ static void deferred_probe_timeout_work_ list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe) dev_info(private->device, "deferred probe pending\n"); - wake_up(&probe_timeout_waitqueue); + wake_up_all(&probe_timeout_waitqueue); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); @@ -487,7 +487,8 @@ static int really_probe(struct device *d drv->bus->name, __func__, drv->name, dev_name(dev)); if (!list_empty(&dev->devres_head)) { dev_crit(dev, "Resources present before probing\n"); - return -EBUSY; + ret = -EBUSY; + goto done; } re_probe: @@ -607,7 +608,7 @@ pinctrl_bind_failed: ret = 0; done: atomic_dec(&probe_count); - wake_up(&probe_waitqueue); + wake_up_all(&probe_waitqueue); return ret; }
