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Date: Tue, 19 Jul 2011 14:24:27 -0400
From: Seiji Aguchi <seiji.aguchi@....com>
To: "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Vivek Goyal <vgoyal@...hat.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Americo Wang <xiyou.wangcong@...il.com>,
Matthew Garrett <mjg@...hat.com>,
"tony.luck@...el.com" <tony.luck@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Jarod Wilson <jwilson@...hat.com>,
"hpa@...or.com" <hpa@...or.com>,
"dzickus@...hat.com" <dzickus@...hat.com>
CC: "dle-develop@...ts.sourceforge.net"
<dle-develop@...ts.sourceforge.net>,
Satoru Moriya <satoru.moriya@....com>
Subject: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to
kexec path
Hi,
This patch adds static function calls so that both pstore and APEI storage backend can work reliably in kexec path.
kernel/kexec.c
- Add pstore_kmsg_dump_in_interrupt(KMSG_DUMP_KEXEC) just after machine_crash_shutdown() so that pstore can
work with one cpu.
kernel/printk.c
- Introduce get_logbuf_nolock() so that pstore can get values of logbuf without taking lock.
fs/pstore/platform.c
- Introduce pstore_kmsg_dump_in_interrupt() so that pstore/APEI storage backend can output kernel messages without taking lock.
pstore_dump()
- Add error checks below because pstore_dump() is called from kmsg_dump(KMSG_DUMP_KEXEC) directly.
- Skip if no driver is registered
- Skip if there is a driver calling pstore_register()/pstore_unregister()
- Remove mutex_lock from kexec path
TODO:
APEI storage backend will work with this patch.
However, I don't have any access to servers capable of APEI storage backend.
Please help to test my patch.
Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
---
fs/pstore/platform.c | 27 +++++++++++++++++++++++++--
include/linux/kmsg_dump.h | 1 +
include/linux/pstore.h | 9 +++++++++
kernel/kexec.c | 3 +++
kernel/printk.c | 29 +++++++++++++++++++++++++++++
5 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index f2c3ff2..85e0a9c 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -74,7 +74,17 @@ static void pstore_dump(struct kmsg_dumper *dumper,
else
why = "Unknown";
- mutex_lock(&psinfo->buf_mutex);
+ switch (reason) {
+ case KMSG_DUMP_KEXEC:
+ /* Skip if there is no driver or there is a driver calling
+ pstore_register() */
+ if (!psinfo || !spin_trylock(&pstore_lock))
+ return;
+ break;
+ default:
+ mutex_lock(&psinfo->buf_mutex);
+ }
+
oopscount++;
while (total < kmsg_bytes) {
dst = psinfo->buf;
@@ -103,7 +113,20 @@ static void pstore_dump(struct kmsg_dumper *dumper,
l2 -= l2_cpy;
total += l1_cpy + l2_cpy;
}
- mutex_unlock(&psinfo->buf_mutex);
+
+ if (reason != KMSG_DUMP_KEXEC)
+ mutex_unlock(&psinfo->buf_mutex);
+}
+
+void pstore_kmsg_dump_in_interrupt(enum kmsg_dump_reason reason)
+{
+ const char *s1, *s2;
+ unsigned long l1, l2;
+
+ /* get logbuf values without spin_lock for avoiding dead lock */
+ get_logbuf_nolock(&s1, &l1, &s2, &l2);
+
+ pstore_dump(NULL, reason, s1, l1, s2, l2);
}
static struct kmsg_dumper pstore_dumper = {
diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index fee6631..ee0c952 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -18,6 +18,7 @@
enum kmsg_dump_reason {
KMSG_DUMP_OOPS,
KMSG_DUMP_PANIC,
+ KMSG_DUMP_KEXEC,
KMSG_DUMP_RESTART,
KMSG_DUMP_HALT,
KMSG_DUMP_POWEROFF,
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 2455ef2..5cf008d 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -22,6 +22,8 @@
#ifndef _LINUX_PSTORE_H
#define _LINUX_PSTORE_H
+#include<linux/kmsg_dump.h>
+
/* types */
enum pstore_type_id {
PSTORE_TYPE_DMESG = 0,
@@ -46,6 +48,9 @@ struct pstore_info {
#ifdef CONFIG_PSTORE
extern int pstore_register(struct pstore_info *);
extern int pstore_write(enum pstore_type_id type, char *buf, size_t size);
+extern void pstore_kmsg_dump_in_interrupt(enum kmsg_dump_reason reason);
+extern void get_logbuf_nolock(const char **s1, unsigned long *l1,
+ const char **s2, unsigned long *l2);
#else
static inline int
pstore_register(struct pstore_info *psi)
@@ -57,6 +62,10 @@ pstore_write(enum pstore_type_id type, char *buf, size_t size)
{
return -ENODEV;
}
+static inline void
+pstore_kmsg_dump_in_interrupt(enum kmsg_dump_reason reason)
+{
+}
#endif
#endif /*_LINUX_PSTORE_H*/
diff --git a/kernel/kexec.c b/kernel/kexec.c
index e24bc1b..8e2761a 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -33,6 +33,8 @@
#include <linux/vmalloc.h>
#include <linux/swap.h>
#include <linux/syscore_ops.h>
+#include <linux/kmsg_dump.h>
+#include <linux/pstore.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1081,6 +1083,7 @@ void crash_kexec(struct pt_regs *regs)
crash_setup_regs(&fixed_regs, regs);
crash_save_vmcoreinfo();
machine_crash_shutdown(&fixed_regs);
+ pstore_kmsg_dump_in_interrupt(KMSG_DUMP_KEXEC);
machine_kexec(kexec_crash_image);
}
mutex_unlock(&kexec_mutex);
diff --git a/kernel/printk.c b/kernel/printk.c
index 37dff34..966a7d9 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1710,6 +1710,35 @@ int kmsg_dump_unregister(struct kmsg_dumper *dumper)
}
EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
+
+void get_logbuf_nolock(const char **s1, unsigned long *l1, const char **s2,
+ unsigned long *l2)
+{
+ unsigned long end;
+ unsigned chars;
+
+ /* Theoretically, the log could move on after we do this, but
+ there's not a lot we can do about that. The new messages
+ will overwrite the start of what we dump. */
+ end = log_end & LOG_BUF_MASK;
+ chars = logged_chars;
+
+ if (chars > end) {
+ *s1 = log_buf + log_buf_len - chars + end;
+ *l1 = chars - end;
+
+ *s2 = log_buf;
+ *l2 = end;
+ } else {
+ *s1 = "";
+ *l1 = 0;
+
+ *s2 = log_buf + end - chars;
+ *l2 = chars;
+ }
+
+}
+
/**
* kmsg_dump - dump kernel log to kernel message dumpers.
* @reason: the reason (oops, panic etc) for dumping
--
1.7.1
--
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