From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 28145272E7C; Wed, 10 Jun 2026 01:29:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781054980; cv=none; b=pehNgAL0XsmVBKO3kmCLNjKlYkN0tcELE0X4OVefsx8uhh239Q+ZXOyVA4UfSfKaIqsbp1wnwxmQoETjZJhq5Ic0wCnuMyFNocmecCbSS2AfYNpJpH12Jrl/l3PS/NPAWSq2cnIsPeSgJqbok5ii6qPUh3GoNysTVHil7h5vhsk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781054980; c=relaxed/simple; bh=BaMBhH4UBV/eRZkCM3tE+1Q0BPtUIU4D6dWPrPx/skw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Qjb9ae9X1tiaU4Zz9jMhLUtBYrLlGNuYEMzIBOOZtDLha/WXJ9BMBhyFvQPn6JV30644EwxwLH/KrLnxH8+16WZ1ZdMmOuJ+2m+V/UC5mh1fMaZZ0lUhQOq/VwE7bg41wu0dY1Ai2qo/hiftriI9MmPY5e+uAo1Bxr7ng0q5gsk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T5VL9X7q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="T5VL9X7q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6A271F00893; Wed, 10 Jun 2026 01:29:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781054979; bh=mcwyzflTFzQMbgkW9om/kpXbBJQYlUaJarM14jOFs1I=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=T5VL9X7qMptDXVDGdYS/8chvo3Mht3G14p/QTb+o2WkMpWISDO1Zaz2TYlPYWNP9t 46RpBd73POBInXOl8zfIWFxdOa8tL3YnwKaEeBhAYbPv9S+kegE6LxQoSMlGvOKILx 0yWh4C24AtH+Xf7rklLX+Nta04SuKkhZXg7Tj6qd6LXHgRXwR1ijRiSxN5bxBVP8Rq Fg5QwAQXsLMagS0vixsTOIeqw5nets7wpdKmyvq0a1KSBMbdJULydCY7aDwvWIs+05 MxHwnigzqNMyu5d5RPjeu3UhQdQVXFfZYtuMG69Y8dSh4/OuSzsEzxmtw40K9Uo+U3 quvFq42QrcZuQ== Date: Wed, 10 Jun 2026 09:29:34 +0800 From: "Peter Chen (CIX)" To: Tyler Baker Cc: Greg Kroah-Hartman , Robert Baldyga , Michal Nazarewicz , Felipe Balbi , stable@vger.kernel.org, Loic Poulain , Dmitry Baryshkov , Srinivas Kandagatla , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] usb: gadget: f_fs: initialize reset_work at allocation time Message-ID: References: <20260609193635.2284430-1-tyler.baker@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260609193635.2284430-1-tyler.baker@oss.qualcomm.com> On 26-06-09 15:36:34, Tyler Baker wrote: > ffs_fs_kill_sb() unconditionally calls cancel_work_sync() on > ffs->reset_work when a functionfs instance is unmounted: > > ffs_data_reset(ffs); > cancel_work_sync(&ffs->reset_work); > > However ffs->reset_work is only ever initialized via INIT_WORK() in > ffs_func_set_alt() and ffs_func_disable(), and only on the > FFS_DEACTIVATED path. That state is reached solely by ffs_data_closed() > when the instance is mounted with the "no_disconnect" option, so for the > common case (no "no_disconnect", or mounted and unmounted without ever > being deactivated) reset_work is never initialized. > > ffs_data_new() allocates the ffs_data with kzalloc_obj() and does not > initialize reset_work, and ffs_data_reset()/ffs_data_clear() do not touch > it either, so reset_work.func is left NULL. cancel_work_sync() on such a > work then trips the WARN_ON(!work->func) guard in __flush_work(): > > WARNING: kernel/workqueue.c:4301 at __flush_work+0x330/0x360, CPU#3: umount > Call trace: > __flush_work > cancel_work_sync > ffs_fs_kill_sb [usb_f_fs] > deactivate_locked_super > deactivate_super > cleanup_mnt > __cleanup_mnt > task_work_run > exit_to_user_mode_loop > el0_svc > > On older kernels cancel_work_sync() on a zero-initialized work struct was > a silent no-op, which hid the missing initialization. > > Initialize reset_work once in ffs_data_new() so it is always valid for > the lifetime of the ffs_data, and drop the now-redundant INIT_WORK() > calls from the two deactivation paths. > > Fixes: 18d6b32fca38 ("usb: gadget: f_fs: add "no_disconnect" mode") > Cc: stable@vger.kernel.org > Signed-off-by: Tyler Baker > Cc: Loic Poulain > Cc: Dmitry Baryshkov > Cc: Srinivas Kandagatla Reviewed-by: Peter Chen Peter > --- > drivers/usb/gadget/function/f_fs.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c > index 75912ce6ab55..1ee21e29ef73 100644 > --- a/drivers/usb/gadget/function/f_fs.c > +++ b/drivers/usb/gadget/function/f_fs.c > @@ -288,6 +288,7 @@ static int ffs_acquire_dev(const char *dev_name, struct ffs_data *ffs_data); > static void ffs_release_dev(struct ffs_dev *ffs_dev); > static int ffs_ready(struct ffs_data *ffs); > static void ffs_closed(struct ffs_data *ffs); > +static void ffs_reset_work(struct work_struct *work); > > /* Misc helper functions ****************************************************/ > > @@ -2221,6 +2222,7 @@ static struct ffs_data *ffs_data_new(const char *dev_name) > init_waitqueue_head(&ffs->ev.waitq); > init_waitqueue_head(&ffs->wait); > init_completion(&ffs->ep0req_completion); > + INIT_WORK(&ffs->reset_work, ffs_reset_work); > > /* XXX REVISIT need to update it in some places, or do we? */ > ffs->ev.can_stall = 1; > @@ -3775,7 +3777,6 @@ static int ffs_func_set_alt(struct usb_function *f, > if (ffs->state == FFS_DEACTIVATED) { > ffs->state = FFS_CLOSING; > spin_unlock_irqrestore(&ffs->eps_lock, flags); > - INIT_WORK(&ffs->reset_work, ffs_reset_work); > schedule_work(&ffs->reset_work); > return -ENODEV; > } > @@ -3806,7 +3807,6 @@ static void ffs_func_disable(struct usb_function *f) > if (ffs->state == FFS_DEACTIVATED) { > ffs->state = FFS_CLOSING; > spin_unlock_irqrestore(&ffs->eps_lock, flags); > - INIT_WORK(&ffs->reset_work, ffs_reset_work); > schedule_work(&ffs->reset_work); > return; > } > -- > 2.43.0 > > -- Best regards, Peter