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Start mcklogd before McKernel to avoid deadlock

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McKernel blocks forever waiting for mcklogd to retrieve kmsg when
kmsg bufer is full with boot log and mcklogd isn't running.
This commit is contained in:
e29005
2016-10-19 16:40:32 +09:00
parent 9705a80c82
commit 0b0aa6c0e0
2 changed files with 26 additions and 6 deletions
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16
arch/x86/tools/mcreboot-smp-x86.sh.in
View File

@ -126,6 +126,16 @@ if [ "${irqbalance_used}" == "yes" ]; then
if ! systemctl stop irqbalance.service 2>/dev/null ; then echo "error: stopping irqbalance" >&2; exit 1; fi;
fi
# Start mcklogd. Note that McKernel blocks when kmsg buffer is full
# with '-k 1' until mcklogd unblocks it so starting mcklogd must preceeds
# booting McKernel
if [ ${LOGMODE} -ne 0 ]
then
# Stop mcklogd which has survived McKernel shutdown because mcstop+release.sh is not used
pkill mcklogd
SBINDIR=${SBINDIR} ${SBINDIR}/mcklogd -i ${INTERVAL} -f ${facility}
fi
# Load IHK if not loaded
if [ "`lsmod | grep ihk`" == "" ]; then
if ! insmod ${KMODDIR}/ihk.ko; then echo "error: loading ihk" >&2; exit 1; fi;
@ -249,12 +259,6 @@ if [ "$enable_mcoverlay" == "yes" ]; then
fi
done
fi
if [ ${LOGMODE} -ne 0 ]
then
# mcklogd survives when McKernel isn't shut down by mcstop+release.sh
pkill mcklogd
SBINDIR=${SBINDIR} ${SBINDIR}/mcklogd -i ${INTERVAL} -f ${facility}
fi
# Start irqbalance with CPUs and IRQ for McKernel banned
if [ "${irqbalance_used}" == "yes" ]; then

16
kernel/debug.c
View File

@ -37,6 +37,8 @@ static void kprintf_wait(int len, unsigned long *flags_head, int *slide) {
if (head < tail) head += buf_len;
if (tail + len > buf_len) adj = buf_len - tail;
if (head > tail && head <= tail + len + adj) {
/* When proceeding tail (producer pointer) by len would
cross head (consumer pointer) in ring-buffer */
if (mode != 1) {
*slide = 1;
break;
@ -70,6 +72,9 @@ void kputs(char *buf)
memcpy(kmsg_buf.str + kmsg_buf.tail, buf, len);
kmsg_buf.tail += len;
/* When proceeding tail (producer pointer) by len would
cross head (consumer pointer) in ring-buffer, give up
[head, tail] because the range is overwritten */
if (slide == 1) {
kmsg_buf.head = kmsg_buf.tail + 1;
if (kmsg_buf.head >= kmsg_buf.len) kmsg_buf.head = 0;
@ -170,6 +175,17 @@ int kprintf(const char *format, ...)
return len;
}
/* mode:
0: mcklogd is not running.
When kmsg buffer is full, writer doesn't block
and overwrites the buffer.
1: mcklogd periodically retrieves kmsg.
When kmsg buffer is full, writer blocks until
someone retrieves kmsg.
2: mcklogd periodically retrieves kmsg.
When kmsg buffer is full, writer doesn't block
and overwrites the buffer.
*/
void kmsg_init(int mode)
{
ihk_mc_spinlock_init(&kmsg_lock);