Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758320AbZLQBi4 (ORCPT ); Wed, 16 Dec 2009 20:38:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756093AbZLQBhv (ORCPT ); Wed, 16 Dec 2009 20:37:51 -0500 Received: from kroah.org ([198.145.64.141]:47976 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753133AbZLQBU0 (ORCPT ); Wed, 16 Dec 2009 20:20:26 -0500 X-Mailbox-Line: From gregkh@mini.kroah.org Wed Dec 16 17:16:03 2009 Message-Id: <20091217011603.362701500@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Wed, 16 Dec 2009 17:14:53 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ian Jackson , Alan Cox Subject: [42/90] Serial: Do not read IIR in serial8250_start_tx when UART_BUG_TXEN In-Reply-To: <20091217011835.GA20434@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1639 Lines: 45 2.6.31-stable review patch. If anyone has any objections, please let us know. ------------------ From: Ian Jackson commit 68cb4f8e246bbbc649980be0628cae9265870a91 upstream. Do not read IIR in serial8250_start_tx when UART_BUG_TXEN Reading the IIR clears some oustanding interrupts so it is not safe. Instead, simply transmit immediately if the buffer is empty without regard to IIR. Signed-off-by: Ian Jackson Reviewed-by: Markus Armbruster Reviewed-by: Jiri Kosina Cc: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/serial/8250.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -1337,14 +1337,12 @@ static void serial8250_start_tx(struct u serial_out(up, UART_IER, up->ier); if (up->bugs & UART_BUG_TXEN) { - unsigned char lsr, iir; + unsigned char lsr; lsr = serial_in(up, UART_LSR); up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; - iir = serial_in(up, UART_IIR) & 0x0f; if ((up->port.type == PORT_RM9000) ? - (lsr & UART_LSR_THRE && - (iir == UART_IIR_NO_INT || iir == UART_IIR_THRI)) : - (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT)) + (lsr & UART_LSR_THRE) : + (lsr & UART_LSR_TEMT)) transmit_chars(up); } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/