From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 76E4412BF32; Tue, 30 Apr 2024 11:29:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714476567; cv=none; b=PHtqkrIgimCvTN4Y78yTOijbMvW3RCVfmOCQqk4ih8x/yRxZrWTnO0MzDoOhhksRZctFu5ae3vgxCgZucmaZdpEoEDCESaObc2Re9i3Fwz3hMKk2QdtoAb4jWAlMbw9VgQtK/Z99UzXzXbV5gdFhStc55ZYR8aeh7hLGCHxWiaU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714476567; c=relaxed/simple; bh=LBXcx3zeYADjd2H7AVArw+n6dtIIduAKI3WJ4R6NQp8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p/yb670QrRJpXGsKpk/ORz+zitWeD2llybM1YiDqO9oE9jREQD2OQ9EFcXj6oqtMub+kHTT9aA3q7jWUsx5Np3VUNm7XhEFkjF3JqE86syfokTGORICks8PH0bLDIrWkV95epxCdO9sfrVxp+s2gcXrhmRk67d4K7o9Iv3LZNkg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a6OHCyxv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="a6OHCyxv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95162C2BBFC; Tue, 30 Apr 2024 11:29:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1714476567; bh=LBXcx3zeYADjd2H7AVArw+n6dtIIduAKI3WJ4R6NQp8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a6OHCyxvFaHlHR5NgrYPW/BeYyx9Oeb80yw665NiBmkmQlbEgIimCk/HNRnHrGCyC fd6c5zu+TZ4RAQuxTuBzteBj1EHPVL/aJGXzJtQVXsgfaZ6eU/T7edVPCVREbS64z5 D27skiBv7V8TBFGVohNcgGbRmhLsbNlVb+dJcveU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nam Cao , Jiri Kosina , Eva Kurchatova Subject: [PATCH 6.1 072/110] HID: i2c-hid: remove I2C_HID_READ_PENDING flag to prevent lock-up Date: Tue, 30 Apr 2024 12:40:41 +0200 Message-ID: <20240430103049.691797296@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240430103047.561802595@linuxfoundation.org> References: <20240430103047.561802595@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nam Cao commit 9c0f59e47a90c54d0153f8ddc0f80d7a36207d0e upstream. The flag I2C_HID_READ_PENDING is used to serialize I2C operations. However, this is not necessary, because I2C core already has its own locking for that. More importantly, this flag can cause a lock-up: if the flag is set in i2c_hid_xfer() and an interrupt happens, the interrupt handler (i2c_hid_irq) will check this flag and return immediately without doing anything, then the interrupt handler will be invoked again in an infinite loop. Since interrupt handler is an RT task, it takes over the CPU and the flag-clearing task never gets scheduled, thus we have a lock-up. Delete this unnecessary flag. Reported-and-tested-by: Eva Kurchatova Closes: https://lore.kernel.org/r/CA+eeCSPUDpUg76ZO8dszSbAGn+UHjcyv8F1J-CUPVARAzEtW9w@mail.gmail.com Fixes: 4a200c3b9a40 ("HID: i2c-hid: introduce HID over i2c specification implementation") Cc: Signed-off-by: Nam Cao Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/hid/i2c-hid/i2c-hid-core.c | 9 --------- 1 file changed, 9 deletions(-) --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -61,7 +61,6 @@ /* flags */ #define I2C_HID_STARTED 0 #define I2C_HID_RESET_PENDING 1 -#define I2C_HID_READ_PENDING 2 #define I2C_HID_PWR_ON 0x00 #define I2C_HID_PWR_SLEEP 0x01 @@ -193,15 +192,10 @@ static int i2c_hid_xfer(struct i2c_hid * msgs[n].len = recv_len; msgs[n].buf = recv_buf; n++; - - set_bit(I2C_HID_READ_PENDING, &ihid->flags); } ret = i2c_transfer(client->adapter, msgs, n); - if (recv_len) - clear_bit(I2C_HID_READ_PENDING, &ihid->flags); - if (ret != n) return ret < 0 ? ret : -EIO; @@ -569,9 +563,6 @@ static irqreturn_t i2c_hid_irq(int irq, { struct i2c_hid *ihid = dev_id; - if (test_bit(I2C_HID_READ_PENDING, &ihid->flags)) - return IRQ_HANDLED; - i2c_hid_get_input(ihid); return IRQ_HANDLED;