[PATCH 3.16.y-ckt 042/104] xhci: init command timeout timer earlier to avoid deleting it uninitialized

From: Luis Henriques
Date: Mon Oct 26 2015 - 10:19:44 EST

3.16.7-ckt19 -stable review patch. If anyone has any objections, please let me know.


From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

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@xxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
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 7b56111c6c7a..f08e81f42951 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);
@@ -2322,6 +2321,10 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)


+ /* 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);
@@ -2506,10 +2509,6 @@ 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).
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