xen: events: Clean up round-robin evtchn scan.
Also fixes a couple of boundary cases.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[ijc: forward ported from linux-2.6.18-xen.hg 988:c88a02a22a05]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 1fc3192..c49cb6d 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1026,8 +1026,8 @@
}
static DEFINE_PER_CPU(unsigned, xed_nesting_count);
-static DEFINE_PER_CPU(unsigned int, last_word_idx) = { BITS_PER_LONG - 1 };
-static DEFINE_PER_CPU(unsigned int, last_bit_idx) = { BITS_PER_LONG - 1 };
+static DEFINE_PER_CPU(unsigned int, current_word_idx);
+static DEFINE_PER_CPU(unsigned int, current_bit_idx);
/*
* Mask out the i least significant bits of w
@@ -1065,23 +1065,21 @@
#endif
pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
- word_idx = __this_cpu_read(last_word_idx);
- bit_idx = __this_cpu_read(last_bit_idx);
+ word_idx = __this_cpu_read(current_word_idx);
+ bit_idx = __this_cpu_read(current_bit_idx);
while (pending_words != 0) {
unsigned long pending_bits;
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 we masked out all events, wrap to beginning.
*/
if (words == 0) {
- word_idx = BITS_PER_LONG - 1;
- bit_idx = BITS_PER_LONG - 1;
+ word_idx = 0;
+ bit_idx = 0;
continue;
}
word_idx = __ffs(words);
@@ -1093,14 +1091,11 @@
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;
+ if (bits == 0)
break;
- }
bit_idx = __ffs(bits);
@@ -1117,22 +1112,23 @@
generic_handle_irq_desc(irq, desc);
}
- /*
- * If this is the final port processed, we'll
- * pick up here+1 next time.
- */
- __this_cpu_write(last_word_idx, word_idx);
- __this_cpu_write(last_bit_idx, bit_idx);
- } while (bit_idx != BITS_PER_LONG - 1);
+ bit_idx = (bit_idx + 1) % BITS_PER_LONG;
+
+ /* Next caller starts at last processed + 1 */
+ __this_cpu_write(current_word_idx,
+ bit_idx ? word_idx :
+ (word_idx+1) % BITS_PER_LONG);
+ __this_cpu_write(current_bit_idx, bit_idx);
+ } while (bit_idx != 0);
pending_bits = active_evtchns(cpu, s, word_idx);
- /*
- * We handled all ports, so we can clear the
- * selector bit.
- */
+ /* If we handled all ports, clear the selector bit. */
if (pending_bits == 0)
pending_words &= ~(1UL << word_idx);
+
+ word_idx = (word_idx + 1) % BITS_PER_LONG;
+ bit_idx = 0;
}
BUG_ON(!irqs_disabled());