[3.16.y-ckt stable] Patch "xhci: init command timeout timer earlier to avoid deleting it uninitialized" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    xhci: init command timeout timer earlier to avoid deleting it uninitialized

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.19.8-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From b218ecf15a5a837a0e505e7ae512bff46883d2c2 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman at linux.intel.com>
Date: Mon, 21 Sep 2015 17:46:17 +0300
Subject: xhci: init command timeout timer earlier to avoid deleting it
 uninitialized

commit cc8e4fc0c3b5e8340bc8358990515d116a3c274c upstream.

Don't check if timer is running with a timer_pending() before
deleting it with del_timer_sync(), this defies the whole point of
the sync part and can cause a possible race.

Instead we just want to make sure the timer is initialized early enough
before we have a chance to delete it.

Reported-by: Oliver Neukum <oneukum at suse.com>
Signed-off-by: Mathias Nyman <mathias.nyman at linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/host/xhci-mem.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 1291417e3..4d45551 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1795,8 +1795,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	int size;
 	int i, j, num_ports;

-	if (timer_pending(&xhci->cmd_timer))
-		del_timer_sync(&xhci->cmd_timer);
+	del_timer_sync(&xhci->cmd_timer);

 	/* Free the Event Ring Segment Table and the actual Event Ring */
 	size = sizeof(struct xhci_erst_entry)*(xhci->erst.num_entries);
@@ -2324,6 +2323,10 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)

 	INIT_LIST_HEAD(&xhci->cmd_list);

+	/* init command timeout timer */
+	setup_timer(&xhci->cmd_timer, xhci_handle_command_timeout,
+		    (unsigned long)xhci);
+
 	page_size = readl(&xhci->op_regs->page_size);
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"Supported page size register = 0x%x", page_size);
@@ -2508,10 +2511,6 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 			"Wrote ERST address to ir_set 0.");
 	xhci_print_ir_set(xhci, 0);

-	/* init command timeout timer */
-	setup_timer(&xhci->cmd_timer, xhci_handle_command_timeout,
-		    (unsigned long)xhci);
-
 	/*
 	 * XXX: Might need to set the Interrupter Moderation Register to
 	 * something other than the default (~1ms minimum between interrupts).
--
1.9.1