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authorFinn Thain <fthain@telegraphics.com.au>2014-11-12 16:12:08 +1100
committerChristoph Hellwig <hch@lst.de>2014-11-20 09:11:13 +0100
commit16b29e75a78ae03250233468b68f7ae467d3dc7a (patch)
treea5ba9e016d5557d2a6f5fb60dc83ae906ae771af /arch/m68k/include/asm
parentcbad48deb38d8e442db9760ca1f950cd24429707 (diff)
atari_scsi: Fix atari_scsi deadlocks on Falcon
Don't disable irqs when waiting for the ST DMA "lock"; its release may require an interrupt. Introduce stdma_try_lock() for use in soft irq context. atari_scsi now tells the SCSI mid-layer to defer queueing a command if the ST DMA lock is not available, as per Michael's patch: http://marc.info/?l=linux-m68k&m=139095335824863&w=2 The falcon_got_lock variable is race prone: we can't disable IRQs while waiting to acquire the lock, so after acquiring it there must be some interval during which falcon_got_lock remains false. Introduce stdma_is_locked_by() to replace falcon_got_lock. The falcon_got_lock tests in the EH handlers are incorrect these days. It can happen that an EH handler is called after a command completes normally. Remove these checks along with falcon_got_lock. Also remove the complicated and racy fairness wait queues. If fairness is an issue (when SCSI competes with IDE for the ST DMA interrupt), the solution is likely to be a lower value for host->can_queue. Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Reviewed-by: Hannes Reinecke <hare@suse.de> Tested-by: Michael Schmitz <schmitzmic@gmail.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'arch/m68k/include/asm')
-rw-r--r--arch/m68k/include/asm/atari_stdma.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/m68k/include/asm/atari_stdma.h b/arch/m68k/include/asm/atari_stdma.h
index 8e389b7fa70..d24e34d870d 100644
--- a/arch/m68k/include/asm/atari_stdma.h
+++ b/arch/m68k/include/asm/atari_stdma.h
@@ -8,11 +8,11 @@
/***************************** Prototypes *****************************/
+int stdma_try_lock(irq_handler_t, void *);
void stdma_lock(irq_handler_t handler, void *data);
void stdma_release( void );
-int stdma_others_waiting( void );
int stdma_islocked( void );
-void *stdma_locked_by( void );
+int stdma_is_locked_by(irq_handler_t);
void stdma_init( void );
/************************* End of Prototypes **************************/