3.16.59-rc1 review patch. If anyone has any objections, please let me know.
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From: Finn Thain fthain@telegraphics.com.au
commit ac39452e942af6a212e8f89e8a36b71354323845 upstream.
The cuda_start() function uses spinlock_irq_save/restore for mutual exclusion. Let's have cuda_poll() do the same when polling the VIA interrupt.
The benefit to disabling local irqs when the interrupt is being polled is that the interrupt handler now has the same timing properties regardless of whether it is invoked normally or from cuda_poll().
This driver was written back when local irqs remained enabled during execution of interrupt handlers and cuda_poll() was probably trying to achieve the same effect by use of enable/disable_irq.
Tested-by: Stan Johnson userm57@yahoo.com Signed-off-by: Finn Thain fthain@telegraphics.com.au Signed-off-by: Michael Ellerman mpe@ellerman.id.au [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/macintosh/via-cuda.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-)
--- a/drivers/macintosh/via-cuda.c +++ b/drivers/macintosh/via-cuda.c @@ -432,26 +432,20 @@ cuda_start(void) void cuda_poll(void) { - /* cuda_interrupt only takes a normal lock, we disable - * interrupts here to avoid re-entering and thus deadlocking. - */ - if (cuda_irq) - disable_irq(cuda_irq); - cuda_interrupt(0, NULL); - if (cuda_irq) - enable_irq(cuda_irq); + cuda_interrupt(0, NULL); }
static irqreturn_t cuda_interrupt(int irq, void *arg) { + unsigned long flags; int status; struct adb_request *req = NULL; unsigned char ibuf[16]; int ibuf_len = 0; int complete = 0;
- spin_lock(&cuda_lock); + spin_lock_irqsave(&cuda_lock, flags);
/* On powermacs, this handler is registered for the VIA IRQ. But they use * just the shift register IRQ -- other VIA interrupt sources are disabled. @@ -464,7 +458,7 @@ cuda_interrupt(int irq, void *arg) #endif { if ((in_8(&via[IFR]) & SR_INT) == 0) { - spin_unlock(&cuda_lock); + spin_unlock_irqrestore(&cuda_lock, flags); return IRQ_NONE; } else { out_8(&via[IFR], SR_INT); @@ -593,7 +587,7 @@ cuda_interrupt(int irq, void *arg) default: printk("cuda_interrupt: unknown cuda_state %d?\n", cuda_state); } - spin_unlock(&cuda_lock); + spin_unlock_irqrestore(&cuda_lock, flags); if (complete && req) { void (*done)(struct adb_request *) = req->done; mb();