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usb: r8a66597-hcd: Fix up spinlock recursion in root hub polling.

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The current root hub polling code exhibits a spinlock recursion on the
private controller lock. r8a66597_root_hub_control() is called from
r8a66597_timer() which grabs the lock and disables IRQs. The following
chain emerges:

  r8a66597_timer() <-- lock taken
    r8a66597_root_hub_control()
      r8a66597_check_syssts()
        usb_hcd_poll_rh_status() <-- acquires the same lock
	/* insert death here */

The entire chain requires IRQs to be disabled, so we just unlock and
relock around the call to usb_hcd_poll_rh_status() while leaving the
IRQ state unchanged.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
This commit is contained in:
Paul Mundt 2010-02-04 06:58:28 +00:00
parent 2717568e7c
commit 2c940db250
1 changed files with 4 additions and 0 deletions
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4
drivers/usb/host/r8a66597-hcd.c
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@ -1022,6 +1022,8 @@ static void start_root_hub_sampling(struct r8a66597 *r8a66597, int port,
/* this function must be called with interrupt disabled */
static void r8a66597_check_syssts(struct r8a66597 *r8a66597, int port,
u16 syssts)
__releases(r8a66597->lock)
__acquires(r8a66597->lock)
{
if (syssts == SE0) {
r8a66597_write(r8a66597, ~ATTCH, get_intsts_reg(port));
@ -1039,7 +1041,9 @@ static void r8a66597_check_syssts(struct r8a66597 *r8a66597, int port,
usb_hcd_resume_root_hub(r8a66597_to_hcd(r8a66597));
}
spin_unlock(&r8a66597->lock);
usb_hcd_poll_rh_status(r8a66597_to_hcd(r8a66597));
spin_lock(&r8a66597->lock);
}
/* this function must be called with interrupt disabled */