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authorGrant Grundler <grundler@parisc-linux.org>2007-06-10 18:31:41 -0400
committerKyle McMartin <kyle@minerva.i.cabal.ca>2007-06-12 01:23:30 -0400
commit462b529f91b618f4bd144bbc6184f616dfb58a1e (patch)
treeeb6cd254ef87ee5b9e3b875023f6368f9747e669 /arch/parisc
parentc3d4ed4e3e5aa8d9e6b4b795f004a7028ce780e9 (diff)
[PARISC] remove global_ack_eiem
Kudos to Thibaut Varene for spotting the (mis)use of appropriately named global_ack_eiem. This took a long time to figure out and both insight from myself, Kyle McMartin, and James Bottomley were required to narrow down which bit of code could have this race condition. The symptom was interrupts stopped getting delivered while some workload was generating IO interrupts on two different CPUs. One of the interrupt sources would get masked off and stay unmasked. Problem was global_ack_eiem was accessed with read/modified/write sequence and not protected by a spinlock. PA-RISC doesn't need a global ack flag though. External Interrupts are _always_ delivered to a single CPU (except for "global broadcast interrupt" which AFAIK currently is not used.) So we don't have to worry about any given IRQ vector getting delivered to more than one CPU. Tested on a500 and rp34xx boxen. rsync to/from gsyprf11 (a500) would lock up the box since NIC (tg3) interrupt and SCSI (sym2) were on "opposite" CPUs (2 CPU system). Put them on the same CPU or apply this patch and 10GB of data would rsync completely. Please apply the following critical patch. thanks, grant Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Acked-by: Thibaut VARENE <T-Bone@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Diffstat (limited to 'arch/parisc')
-rw-r--r--arch/parisc/kernel/irq.c26
1 files changed, 8 insertions, 18 deletions
diff --git a/arch/parisc/kernel/irq.c b/arch/parisc/kernel/irq.c
index c5c9125dacec..76ce5e3b0050 100644
--- a/arch/parisc/kernel/irq.c
+++ b/arch/parisc/kernel/irq.c
@@ -46,14 +46,10 @@ extern irqreturn_t ipi_interrupt(int, void *);
46static volatile unsigned long cpu_eiem = 0; 46static volatile unsigned long cpu_eiem = 0;
47 47
48/* 48/*
49** ack bitmap ... habitually set to 1, but reset to zero 49** local ACK bitmap ... habitually set to 1, but reset to zero
50** between ->ack() and ->end() of the interrupt to prevent 50** between ->ack() and ->end() of the interrupt to prevent
51** re-interruption of a processing interrupt. 51** re-interruption of a processing interrupt.
52*/ 52*/
53static volatile unsigned long global_ack_eiem = ~0UL;
54/*
55** Local bitmap, same as above but for per-cpu interrupts
56*/
57static DEFINE_PER_CPU(unsigned long, local_ack_eiem) = ~0UL; 53static DEFINE_PER_CPU(unsigned long, local_ack_eiem) = ~0UL;
58 54
59static void cpu_disable_irq(unsigned int irq) 55static void cpu_disable_irq(unsigned int irq)
@@ -94,13 +90,11 @@ void cpu_ack_irq(unsigned int irq)
94 int cpu = smp_processor_id(); 90 int cpu = smp_processor_id();
95 91
96 /* Clear in EIEM so we can no longer process */ 92 /* Clear in EIEM so we can no longer process */
97 if (CHECK_IRQ_PER_CPU(irq_desc[irq].status)) 93 per_cpu(local_ack_eiem, cpu) &= ~mask;
98 per_cpu(local_ack_eiem, cpu) &= ~mask;
99 else
100 global_ack_eiem &= ~mask;
101 94
102 /* disable the interrupt */ 95 /* disable the interrupt */
103 set_eiem(cpu_eiem & global_ack_eiem & per_cpu(local_ack_eiem, cpu)); 96 set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
97
104 /* and now ack it */ 98 /* and now ack it */
105 mtctl(mask, 23); 99 mtctl(mask, 23);
106} 100}
@@ -111,13 +105,10 @@ void cpu_end_irq(unsigned int irq)
111 int cpu = smp_processor_id(); 105 int cpu = smp_processor_id();
112 106
113 /* set it in the eiems---it's no longer in process */ 107 /* set it in the eiems---it's no longer in process */
114 if (CHECK_IRQ_PER_CPU(irq_desc[irq].status)) 108 per_cpu(local_ack_eiem, cpu) |= mask;
115 per_cpu(local_ack_eiem, cpu) |= mask;
116 else
117 global_ack_eiem |= mask;
118 109
119 /* enable the interrupt */ 110 /* enable the interrupt */
120 set_eiem(cpu_eiem & global_ack_eiem & per_cpu(local_ack_eiem, cpu)); 111 set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
121} 112}
122 113
123#ifdef CONFIG_SMP 114#ifdef CONFIG_SMP
@@ -354,8 +345,7 @@ void do_cpu_irq_mask(struct pt_regs *regs)
354 local_irq_disable(); 345 local_irq_disable();
355 irq_enter(); 346 irq_enter();
356 347
357 eirr_val = mfctl(23) & cpu_eiem & global_ack_eiem & 348 eirr_val = mfctl(23) & cpu_eiem & per_cpu(local_ack_eiem, cpu);
358 per_cpu(local_ack_eiem, cpu);
359 if (!eirr_val) 349 if (!eirr_val)
360 goto set_out; 350 goto set_out;
361 irq = eirr_to_irq(eirr_val); 351 irq = eirr_to_irq(eirr_val);
@@ -381,7 +371,7 @@ void do_cpu_irq_mask(struct pt_regs *regs)
381 return; 371 return;
382 372
383 set_out: 373 set_out:
384 set_eiem(cpu_eiem & global_ack_eiem & per_cpu(local_ack_eiem, cpu)); 374 set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
385 goto out; 375 goto out;
386} 376}
387 377