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 2BBCC378D7D; Tue, 14 Jul 2026 02:53:28 +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=1783997610; cv=none; b=MdzEGFT4AJ81VYgNhDsVToDrW7o8MuZMznaes9IHMsaNvoNsJ+HOxDAXZ0jVpc3rLa14DcGyTaiDuTV16mqqn99DJQH17SXwanz7Ld+CDSty223TFbx/ODXS+5GtdEj1affUqKiQ3P6XsysB3PpLDedByWooxaGwFiKk2q6QRTI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783997610; c=relaxed/simple; bh=NVJEBYnjUAbOEmeXumg06ZQmEpkEW60hwM7Li9XCGLU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RTK68kkAIQzidMfTStgJ/gdpZ0F1yhewuJDjJ42UdPGmiJM2PZl/rQvyww6EO/xzD+CqjdAUwA0nzZPdt+X0D5LAatec6Oy3/mlH3YnuTbCSFDwVFkBeb3ysEAqlBleLbKFZij4DcJO9gq+zrt43QwQjXbg8z3kvxxbX8AnX7Yk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LUcKxUjY; 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="LUcKxUjY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A45B1F000E9; Tue, 14 Jul 2026 02:53:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783997608; bh=b0YkISUvD66GFsQjNiTygrNgFmIa2vyWu5o957KGl9o=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=LUcKxUjYDlMXLD5VlEfPVWx7qilnoL0KFfalNjDtbZFA/WlZReayDkAuql3+lJizP VSwkAQABOxzE+OKlyuBQ2NQqc4OgdzReR0lNMpxbuIOQz6gMCiApxk/W50R5DM1JM5 5+M3ZWnJcovaEH9p7F6RgkSF7cxiUKouDHsYxhbe6lvN3NJB1tp7mBXvoAv0ezNyOR 629BpT3YPWM18rrbv7VbLjkKaPywhY7RdTeBzNvWgQd3d1ZZnolTXEmjI10xsjkNZ1 dAqUn+WK7fo8DVldZ0Hu8qbBoK0nryBiDdlm2vnwVGYaBb5Bbe5k0eHCCgg6vrHxhA sZirHSNj3qH1g== Date: Mon, 13 Jul 2026 21:53:25 -0500 From: Bjorn Andersson To: Vishnu Santhosh Cc: Mathieu Poirier , linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn.andersson@oss.qualcomm.com, chris.lew@oss.qualcomm.com, Deepak Kumar Singh Subject: Re: [PATCH] rpmsg: glink: fix deadlock in endpoint destroy during driver detach Message-ID: References: <20260604-rpmsg-glink-fix-deadlock-destroy-ept-v1-1-b8a54ad1e4fd@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 Content-Transfer-Encoding: 8bit In-Reply-To: <20260604-rpmsg-glink-fix-deadlock-destroy-ept-v1-1-b8a54ad1e4fd@oss.qualcomm.com> On Thu, Jun 04, 2026 at 02:12:53PM +0530, Vishnu Santhosh wrote: > During driver detach, the device core holds the device mutex throughout > the driver's remove callback chain. When the rpmsg endpoint is > destroyed as part of that teardown, the GLINK endpoint destroy > implementation attempts to unregister the underlying rpmsg device. > That unregistration calls device_del(), which tries to re-acquire the > same device mutex already held higher up the stack, causing rmmod to > hang indefinitely. > > The deadlock manifests with the following call chain: > > [<0>] device_del+0x44/0x414  <- tries to acquire same mutex > [<0>] device_unregister+0x18/0x34 > [<0>] rpmsg_unregister_device+0x28/0x4c > [<0>] qcom_glink_remove_rpmsg_device+0x70/0xc0 > [<0>] qcom_glink_destroy_ept+0x58/0xbc > [<0>] rpmsg_dev_remove+0x50/0x60 > [<0>] device_remove+0x4c/0x80 > [<0>] device_release_driver_internal+0x1cc/0x228 <- acquires device mutex > [<0>] driver_detach+0x4c/0x98 > [<0>] bus_remove_driver+0x6c/0xbc > [<0>] driver_unregister+0x30/0x60 > [<0>] unregister_rpmsg_driver+0x10/0x1c > [<0>] fastrpc_exit+0x28/0x38 [fastrpc] > [<0>] __arm64_sys_delete_module+0x1b8/0x294 > [<0>] invoke_syscall+0x48/0x10c > [<0>] el0_svc_common.constprop.0+0xc0/0xe0 > [<0>] do_el0_svc+0x1c/0x28 > [<0>] el0_svc+0x34/0x108 > [<0>] el0t_64_sync_handler+0xa0/0xe4 > [<0>] el0t_64_sync+0x198/0x19c > > The rpmsg device unregistration inside endpoint destroy is redundant. > In both contexts where endpoint destruction is triggered: > > - Driver detach path: the driver core already tears down the rpmsg > device. > > - Channel close path: the rpmsg device is already unregistered before > endpoint destruction is reached. > > Remove the redundant unregistration to fix the deadlock. > > Co-developed-by: Deepak Kumar Singh > Signed-off-by: Deepak Kumar Singh > Signed-off-by: Vishnu Santhosh Tested-by: Bjorn Andersson Regards, Bjorn > --- > drivers/rpmsg/qcom_glink_native.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c > index 401a4ece0c9777398837d4427746fae0a5003e88..ab7ff3d2f56bf797592fc4227ce5b730bce72226 100644 > --- a/drivers/rpmsg/qcom_glink_native.c > +++ b/drivers/rpmsg/qcom_glink_native.c > @@ -1418,9 +1418,6 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept) > channel->ept.cb = NULL; > spin_unlock_irqrestore(&channel->recv_lock, flags); > > - /* Decouple the potential rpdev from the channel */ > - qcom_glink_remove_rpmsg_device(glink, channel); > - > qcom_glink_send_close_req(glink, channel); > } > > > --- > base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8 > change-id: 20260416-rpmsg-glink-fix-deadlock-destroy-ept-5cc7aac522a0 > > Best regards, > -- > Vishnu Santhosh >