From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751563AbcLEIBb (ORCPT ); Mon, 5 Dec 2016 03:01:31 -0500 Received: from mail-pg0-f44.google.com ([74.125.83.44]:33212 "EHLO mail-pg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751039AbcLEIB2 (ORCPT ); Mon, 5 Dec 2016 03:01:28 -0500 From: Baolin Wang To: mathias.nyman@intel.com, gregkh@linuxfoundation.org Cc: baolu.lu@linux.intel.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, broonie@kernel.org, baolin.wang@linaro.org Subject: [PATCH 2/2] usb: host: xhci: Handle the right timeout command Date: Mon, 5 Dec 2016 15:51:50 +0800 Message-Id: <0c39bfed1cf6f7b747e702aa841f82c9d2140f27.1480922249.git.baolin.wang@linaro.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a command event is found on the event ring during an interrupt, we need to stop the command timer with del_timer(). Since del_timer() can fail if the timer is running and waiting on the xHCI lock, then it maybe get the wrong timeout command in xhci_handle_command_timeout() if host fetched a new command and updated the xhci->current_cmd in handle_cmd_completion(). For this situation, we need a way to signal to the command timer that everything is fine and it should exit. We should introduce a counter (xhci->current_cmd_pending) for the number of pending commands. If we need to cancel the command timer and del_timer() succeeds, we decrement the number of pending commands. If del_timer() fails, we leave the number of pending commands alone. For handling timeout command, in xhci_handle_command_timeout() we will check the counter after decrementing it, if the counter (xhci->current_cmd_pending) is 0, which means xhci->current_cmd is the right timeout command. If the counter (xhci->current_cmd_pending) is greater than 0, which means current timeout command has been handled by host and host has fetched new command as xhci->current_cmd, then just return and wait for new current command. Signed-off-by: Baolin Wang --- drivers/usb/host/xhci-ring.c | 29 ++++++++++++++++++++++++++++- drivers/usb/host/xhci.h | 1 + 2 files changed, 29 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 9965a4c..edc9ac2 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1253,6 +1253,7 @@ static void xhci_handle_stopped_cmd_ring(struct xhci_hcd *xhci, if ((xhci->cmd_ring->dequeue != xhci->cmd_ring->enqueue) && !(xhci->xhc_state & XHCI_STATE_DYING)) { xhci->current_cmd = cur_cmd; + xhci->current_cmd_pending++; mod_timer(&xhci->cmd_timer, jiffies + XHCI_CMD_DEFAULT_TIMEOUT); xhci_ring_cmd_db(xhci); } @@ -1269,11 +1270,27 @@ void xhci_handle_command_timeout(unsigned long data) xhci = (struct xhci_hcd *) data; spin_lock_irqsave(&xhci->lock, flags); + xhci->current_cmd_pending--; + if (!xhci->current_cmd) { spin_unlock_irqrestore(&xhci->lock, flags); return; } + /* + * If the current_cmd_pending is 0, which means current command is + * timeout. + * + * If the current_cmd_pending is greater than 0, which means current + * timeout command has been handled by host and host has fetched new + * command as xhci->current_cmd, then just return and wait for new + * current command. + */ + if (xhci->current_cmd_pending > 0) { + spin_unlock_irqrestore(&xhci->lock, flags); + return; + } + if (xhci->current_cmd->status == COMP_CMD_ABORT) second_timeout = true; xhci->current_cmd->status = COMP_CMD_ABORT; @@ -1282,6 +1299,8 @@ void xhci_handle_command_timeout(unsigned long data) hw_ring_state = xhci_read_64(xhci, &xhci->op_regs->cmd_ring); if ((xhci->cmd_ring_state & CMD_RING_STATE_RUNNING) && (hw_ring_state & CMD_RING_RUNNING)) { + /* Will add command timer again to wait for abort event */ + xhci->current_cmd_pending++; spin_unlock_irqrestore(&xhci->lock, flags); xhci_dbg(xhci, "Command timeout\n"); ret = xhci_abort_cmd_ring(xhci); @@ -1336,7 +1355,13 @@ static void handle_cmd_completion(struct xhci_hcd *xhci, cmd = list_entry(xhci->cmd_list.next, struct xhci_command, cmd_list); - del_timer(&xhci->cmd_timer); + /* + * If the command timer is running on another CPU, we don't decrement + * current_cmd_pending, since we didn't successfully stop the command + * timer. + */ + if (del_timer(&xhci->cmd_timer)) + xhci->current_cmd_pending--; trace_xhci_cmd_completion(cmd_trb, (struct xhci_generic_trb *) event); @@ -1427,6 +1452,7 @@ static void handle_cmd_completion(struct xhci_hcd *xhci, if (cmd->cmd_list.next != &xhci->cmd_list) { xhci->current_cmd = list_entry(cmd->cmd_list.next, struct xhci_command, cmd_list); + xhci->current_cmd_pending++; mod_timer(&xhci->cmd_timer, jiffies + XHCI_CMD_DEFAULT_TIMEOUT); } else if (xhci->current_cmd == cmd) { xhci->current_cmd = NULL; @@ -3927,6 +3953,7 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd, if (xhci->cmd_list.next == &cmd->cmd_list && !timer_pending(&xhci->cmd_timer)) { xhci->current_cmd = cmd; + xhci->current_cmd_pending++; mod_timer(&xhci->cmd_timer, jiffies + XHCI_CMD_DEFAULT_TIMEOUT); } diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 9dbaacf..5d81257 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1567,6 +1567,7 @@ struct xhci_hcd { unsigned int cmd_ring_reserved_trbs; struct timer_list cmd_timer; struct xhci_command *current_cmd; + u32 current_cmd_pending; struct xhci_ring *event_ring; struct xhci_erst erst; /* Scratchpad */ -- 1.7.9.5