driver core: Fix probe_count imbalance in really_probe()

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@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.ne.jp
[iwamatsu: Drop patch for deferred_probe_timeout_work_func()]
Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 1d5dd37f3abe467c1c3b1f03e36641464647db6a..84e757860ebb94180fe3b0149e253e5c5f0e8e13 100644 (file)
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -518,7 +518,8 @@ 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:
@@ -639,7 +640,7 @@ pinctrl_bind_failed:
        ret = 0;
 done:
        atomic_dec(&probe_count);
-       wake_up(&probe_waitqueue);
+       wake_up_all(&probe_waitqueue);
        return ret;
 }