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Subject[PATCH 03/10] x86, mce: change writer timeout in mce_read
Changed to use ndelay().

(This piece originates from Huang's patch, titled:
"x86, MCE: Fix bugs and issues of MCE log ring buffer")

Originally-From: Huang Ying <ying.huang@intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
---
arch/x86/kernel/cpu/mcheck/mce.c | 11 ++++++++---
1 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 2d0f9d8..9e8eabd 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -52,6 +52,9 @@ int mce_disabled __read_mostly;

#define SPINUNIT 100 /* 100ns */

+/* Timeout log reader to wait writer to finish */
+#define WRITER_TIMEOUT_NS NSEC_PER_MSEC
+
atomic_t mce_entry;

DEFINE_PER_CPU(unsigned, mce_exception_count);
@@ -1469,15 +1472,17 @@ static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize,
prev = 0;
do {
for (i = prev; i < next; i++) {
- unsigned long start = jiffies;
+ int timeout = WRITER_TIMEOUT_NS;

while (!mcelog.entry[i].finished) {
- if (time_after_eq(jiffies, start + 2)) {
+ if (timeout-- <= 0) {
memset(mcelog.entry + i, 0,
sizeof(struct mce));
+ printk(KERN_WARNING "mcelog: timeout "
+ "waiting for writer to finish!\n");
goto timeout;
}
- cpu_relax();
+ ndelay(1);
}
smp_rmb();
err |= copy_to_user(buf, mcelog.entry + i,
--
1.6.4.3



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