From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp

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=25c833f1983c9c1d512f4ff860dd0d7f5a2e2c0...

Reported-by: syzbot syzbot+805f5f6ae37411f15b64@syzkaller.appspotmail.com Fixes: 7c35e699c88bd607 ("driver core: Print device when resources present in really_probe()") Cc: Geert Uytterhoeven geert+renesas@glider.be Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Cc: stable stable@kernel.org Link: https://lore.kernel.org/r/20200713021254.3444-1-penguin-kernel@I-love.SAKURA... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [iwamatsu: Drop patch for deferred_probe_timeout_work_func()] Signed-off-by: Nobuhiro Iwamatsu (CIP) nobuhiro1.iwamatsu@toshiba.co.jp --- drivers/base/dd.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 0047bbdd43c0f0..b3c569412f4e2e 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -472,7 +472,8 @@ static int really_probe(struct device *dev, struct device_driver *drv) 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: @@ -579,7 +580,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) ret = 0; done: atomic_dec(&probe_count); - wake_up(&probe_waitqueue); + wake_up_all(&probe_waitqueue); return ret; }

-- 2.28.0