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Subject[PATCH v1 2/2] mtd: mtdoops: panic caused mtdoops to call mtd erase function immediately
From
The panic function disables the local interrupts, preemption, and all
other processors. When the invoked mtdoops needs to erase a used page,
calling schedule_work() to do it will not work. Instead, just call mtd
erase function immediately.

Tested:
~# echo c > /proc/sysrq-trigger
[ 171.654759] sysrq: Trigger a crash
[ 171.658325] Kernel panic - not syncing: sysrq triggered crash
......
[ 172.406423] mtdoops: not ready 34, 35 (erase immediately)
[ 172.432285] mtdoops: ready 34, 35
[ 172.435633] Rebooting in 10 seconds..

Signed-off-by: Ray Zhang <sgzhang@google.com>
---
drivers/mtd/mtdoops.c | 66 ++++++++++++++++++++++++++-----------------
1 file changed, 40 insertions(+), 26 deletions(-)

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 84b21be347f6..73c6a55eb391 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -106,29 +106,8 @@ static int mtdoops_erase_block(struct mtdoops_context *cxt, int offset)
return 0;
}

-static void mtdoops_inc_counter(struct mtdoops_context *cxt)
+static void mtdoops_erase(struct mtdoops_context *cxt)
{
- cxt->nextpage++;
- if (cxt->nextpage >= cxt->oops_pages)
- cxt->nextpage = 0;
- cxt->nextcount++;
- if (cxt->nextcount == 0xffffffff)
- cxt->nextcount = 0;
-
- if (page_is_used(cxt, cxt->nextpage)) {
- schedule_work(&cxt->work_erase);
- return;
- }
-
- pr_debug("mtdoops: ready %d, %d (no erase)\n",
- cxt->nextpage, cxt->nextcount);
-}
-
-/* Scheduled work - when we can't proceed without erasing a block */
-static void mtdoops_workfunc_erase(struct work_struct *work)
-{
- struct mtdoops_context *cxt =
- container_of(work, struct mtdoops_context, work_erase);
struct mtd_info *mtd = cxt->mtd;
int i = 0, j, ret, mod;

@@ -166,8 +145,8 @@ static void mtdoops_workfunc_erase(struct work_struct *work)
ret = mtdoops_erase_block(cxt, cxt->nextpage * record_size);

if (ret >= 0) {
- pr_debug("mtdoops: ready %d, %d\n",
- cxt->nextpage, cxt->nextcount);
+ pr_notice("mtdoops: ready %d, %d\n",
+ cxt->nextpage, cxt->nextcount);
return;
}

@@ -181,6 +160,41 @@ static void mtdoops_workfunc_erase(struct work_struct *work)
goto badblock;
}

+/* Scheduled work - when we can't proceed without erasing a block */
+static void mtdoops_workfunc_erase(struct work_struct *work)
+{
+ struct mtdoops_context *cxt =
+ container_of(work, struct mtdoops_context, work_erase);
+
+ mtdoops_erase(cxt);
+}
+
+static void mtdoops_inc_counter(struct mtdoops_context *cxt, int panic)
+{
+ cxt->nextpage++;
+ if (cxt->nextpage >= cxt->oops_pages)
+ cxt->nextpage = 0;
+ cxt->nextcount++;
+ if (cxt->nextcount == 0xffffffff)
+ cxt->nextcount = 0;
+
+ if (page_is_used(cxt, cxt->nextpage)) {
+ pr_notice("mtdoops: not ready %d, %d (erase %s)\n",
+ cxt->nextpage, cxt->nextcount,
+ panic ? "immediately" : "scheduled");
+ if (panic) {
+ /* In case of panic, erase immediately */
+ mtdoops_erase(cxt);
+ } else {
+ /* Otherwise, schedule work to erase it "nicely" */
+ schedule_work(&cxt->work_erase);
+ }
+ } else {
+ pr_notice("mtdoops: ready %d, %d (no erase)\n",
+ cxt->nextpage, cxt->nextcount);
+ }
+}
+
static void mtdoops_write(struct mtdoops_context *cxt, int panic)
{
struct mtd_info *mtd = cxt->mtd;
@@ -214,7 +228,7 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
mark_page_used(cxt, cxt->nextpage);
memset(cxt->oops_buf, 0xff, record_size);

- mtdoops_inc_counter(cxt);
+ mtdoops_inc_counter(cxt, panic);
out:
clear_bit(0, &cxt->oops_buf_busy);
}
@@ -279,7 +293,7 @@ static void find_next_position(struct mtdoops_context *cxt)
cxt->nextcount = maxcount;
}

- mtdoops_inc_counter(cxt);
+ mtdoops_inc_counter(cxt, 0);
}

static void mtdoops_do_dump(struct kmsg_dumper *dumper,
--
2.37.3.998.g577e59143f-goog
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