From: Stephen Rothwell Date: Wed, 12 Dec 2007 03:58:12 +0000 (+1100) Subject: [POWERPC] iSeries: don't printk with HV spinlock held X-Git-Tag: v2.6.24-rc6~70^2~2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=88f0178e6ec2c73167de973e4af86905b4dbfd45;p=linux-2.6 [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 --- diff --git a/arch/powerpc/platforms/iseries/lpevents.c b/arch/powerpc/platforms/iseries/lpevents.c index 34bdbbe3ce..275f494498 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)