cbus-retu: Add locking around register access in irq handler

This adds locking around the register access in the interrupt service routine.

---

Index: linux-omap-2.6/drivers/cbus/retu.c
===================================================================
@@ -198,10 +198,12 @@ static irqreturn_t retu_irq_handler(int
 	u16			idr;
 	u16			imr;
 
+	mutex_lock(&retu->mutex);
 	idr = __retu_read_reg(retu, RETU_REG_IDR);
 	imr = __retu_read_reg(retu, RETU_REG_IMR);
-	idr &= ~imr;
+	mutex_unlock(&retu->mutex);
 
+	idr &= ~imr;
 	if (!idr) {
 		dev_vdbg(retu->dev, "No IRQ, spurious?\n");
 		return IRQ_NONE;

Fine by me. Tony, you can apply.

balbi

Only applied the first two to add the register defines because of:

BUG: sleeping function called from invalid context at kernel/mutex.c:278

in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper
INFO: lockdep is turned off.
[<c0063c24>] (unwind_backtrace+0x0/0xec) from [<c0402f98>] (mutex_lock_nested+0x24/0x340) [<c0402f98>] (mutex_lock_nested+0x24/0x340) from [<c032b4e4>] (retu_write_reg+0x20/0x3c) [<c032b4e4>] (retu_write_reg+0x20/0x3c) from [<c032bc4c>] (_retu_modify_counter+0x28/0x34) [<c032bc4c>] (_retu_modify_counter+0x28/0x34) from [<c032be48>] (retu_wdt_set_ping_timer+0x10/0x50) [<c032be48>] (retu_wdt_set_ping_timer+0x10/0x50) from [<c00a2000>] (run_timer_softirq+0x260/0x368) [<c00a2000>] (run_timer_softirq+0x260/0x368) from [<c009bdb8>] (__do_softirq+0xe8/0x1e0) [<c009bdb8>] (__do_softirq+0xe8/0x1e0) from [<c009bf04>] (irq_exit+0x54/0xa0) [<c009bf04>] (irq_exit+0x54/0xa0) from [<c0052090>] (asm_do_IRQ+0x90/0xcc) [<c0052090>] (asm_do_IRQ+0x90/0xcc) from [<c0404adc>] (__irq_svc+0x3c/0x100)

Tony