From 88f0178e6ec2c73167de973e4af86905b4dbfd45 Mon Sep 17 00:00:00 2001 From: Stephen Rothwell Date: Wed, 12 Dec 2007 14:58:12 +1100 Subject: [PATCH] [POWERPC] iSeries: don't printk with HV spinlock held Printk was observed to hang during module unload due to a limited window of characters that may be sent to the hypervisor. The window only reexpands when we receive an ack from the HV and the spinlock here prevents us from ever processing that ack. This fixes it by dropping the lock before doing the printk, then looping back to the top to reacquire the lock. Signed-off-by: Stephen Rothwell Signed-off-by: Paul Mackerras --- arch/powerpc/platforms/iseries/lpevents.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/iseries/lpevents.c b/arch/powerpc/platforms/iseries/lpevents.c index 34bdbbe3ce5..275f4944983 100644 --- a/arch/powerpc/platforms/iseries/lpevents.c +++ b/arch/powerpc/platforms/iseries/lpevents.c @@ -121,6 +121,7 @@ void process_hvlpevents(void) { struct HvLpEvent * event; + restart: /* If we have recursed, just return */ if (!spin_trylock(&hvlpevent_queue.hq_lock)) return; @@ -146,8 +147,20 @@ void process_hvlpevents(void) if (event->xType < HvLpEvent_Type_NumTypes && lpEventHandler[event->xType]) lpEventHandler[event->xType](event); - else - printk(KERN_INFO "Unexpected Lp Event type=%d\n", event->xType ); + else { + u8 type = event->xType; + + /* + * Don't printk in the spinlock as printk + * may require ack events form the HV to send + * any characters there. + */ + hvlpevent_clear_valid(event); + spin_unlock(&hvlpevent_queue.hq_lock); + printk(KERN_INFO + "Unexpected Lp Event type=%d\n", type); + goto restart; + } hvlpevent_clear_valid(event); } else if (hvlpevent_queue.hq_overflow_pending) -- 2.11.4.GIT