diff options
| -rw-r--r-- | drivers/xen/events.c | 72 |
1 files changed, 65 insertions, 7 deletions
diff --git a/drivers/xen/events.c b/drivers/xen/events.c index 6befe6227159..75cc6f50bd29 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -1028,6 +1028,11 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id) static DEFINE_PER_CPU(unsigned, xed_nesting_count); /* + * Mask out the i least significant bits of w + */ +#define MASK_LSBS(w, i) (w & ((~0UL) << i)) + +/* * Search the CPUs pending events bitmasks. For each one found, map * the event number to an irq, and feed it into do_IRQ() for * handling. @@ -1038,6 +1043,9 @@ static DEFINE_PER_CPU(unsigned, xed_nesting_count); */ static void __xen_evtchn_do_upcall(void) { + static unsigned int last_word_idx = BITS_PER_LONG - 1; + static unsigned int last_bit_idx = BITS_PER_LONG - 1; + int word_idx, bit_idx; int cpu = get_cpu(); struct shared_info *s = HYPERVISOR_shared_info; struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); @@ -1056,17 +1064,50 @@ static void __xen_evtchn_do_upcall(void) wmb(); #endif pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0); + + word_idx = last_word_idx; + bit_idx = last_bit_idx; + while (pending_words != 0) { unsigned long pending_bits; - int word_idx = __ffs(pending_words); - pending_words &= ~(1UL << word_idx); + unsigned long words; + + word_idx = (word_idx + 1) % BITS_PER_LONG; + words = MASK_LSBS(pending_words, word_idx); + + /* + * If we masked out all events, wrap around to the + * beginning. + */ + if (words == 0) { + word_idx = BITS_PER_LONG - 1; + bit_idx = BITS_PER_LONG - 1; + continue; + } + word_idx = __ffs(words); - while ((pending_bits = active_evtchns(cpu, s, word_idx)) != 0) { - int bit_idx = __ffs(pending_bits); - int port = (word_idx * BITS_PER_LONG) + bit_idx; - int irq = evtchn_to_irq[port]; + do { + unsigned long bits; + int port, irq; struct irq_desc *desc; + pending_bits = active_evtchns(cpu, s, word_idx); + + bit_idx = (bit_idx + 1) % BITS_PER_LONG; + bits = MASK_LSBS(pending_bits, bit_idx); + + /* If we masked out all events, move on. */ + if (bits == 0) { + bit_idx = BITS_PER_LONG - 1; + break; + } + + bit_idx = __ffs(bits); + + /* Process port. */ + port = (word_idx * BITS_PER_LONG) + bit_idx; + irq = evtchn_to_irq[port]; + mask_evtchn(port); clear_evtchn(port); @@ -1075,7 +1116,24 @@ static void __xen_evtchn_do_upcall(void) if (desc) generic_handle_irq_desc(irq, desc); } - } + + /* + * If this is the final port processed, we'll + * pick up here+1 next time. + */ + last_word_idx = word_idx; + last_bit_idx = bit_idx; + + } while (bit_idx != BITS_PER_LONG - 1); + + pending_bits = active_evtchns(cpu, s, word_idx); + + /* + * We handled all ports, so we can clear the + * selector bit. + */ + if (pending_bits == 0) + pending_words &= ~(1UL << word_idx); } BUG_ON(!irqs_disabled()); |
