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authorRichard Purdie <rpurdie@rpsys.net>2008-02-06 10:17:15 +0000
committerDavid Woodhouse <dwmw2@infradead.org>2008-02-07 10:30:48 +0000
commit388bbb09b991c792310af2f6b49f6c55edb3dff0 (patch)
treeca390147bddbf27587316911f69e1544f4592904 /drivers/mtd/mtdpart.c
parent76b104671632c225ad594a50f9e26ada67bc0a74 (diff)
[MTD] Add mtd panic_write function pointer
MTDs are well suited for logging critical data and the mtdoops driver allows kernel panics/oops to be written to flash in a blackbox flight recorder fashion allowing better debugging and analysis of crashes. Any kernel oops in user context can be easily handled since the kernel continues as normal and any queued mtd writes are scheduled. Any kernel oops in interrupt context results in a panic and the delayed writes will not be scheduled however. The existing mtd->write function cannot be called in interrupt context so these messages can never be written to flash. This patch adds a panic_write function pointer that drivers can optionally implement which can be called in interrupt context. It is only intended to be called when its known the kernel is about to panic and we need to write to succeed. Since the kernel is not going to be running for much longer, this function can break locks and delay to ensure the write succeeds (but not sleep). Signed-off-by: Richard Purdie <rpurdie@rpsys.net> Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Diffstat (limited to 'drivers/mtd/mtdpart.c')
-rw-r--r--drivers/mtd/mtdpart.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 6174a97d790..c66902df317 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -151,6 +151,20 @@ static int part_write (struct mtd_info *mtd, loff_t to, size_t len,
len, retlen, buf);
}
+static int part_panic_write (struct mtd_info *mtd, loff_t to, size_t len,
+ size_t *retlen, const u_char *buf)
+{
+ struct mtd_part *part = PART(mtd);
+ if (!(mtd->flags & MTD_WRITEABLE))
+ return -EROFS;
+ if (to >= mtd->size)
+ len = 0;
+ else if (to + len > mtd->size)
+ len = mtd->size - to;
+ return part->master->panic_write (part->master, to + part->offset,
+ len, retlen, buf);
+}
+
static int part_write_oob(struct mtd_info *mtd, loff_t to,
struct mtd_oob_ops *ops)
{
@@ -352,6 +366,9 @@ int add_mtd_partitions(struct mtd_info *master,
slave->mtd.read = part_read;
slave->mtd.write = part_write;
+ if (master->panic_write)
+ slave->mtd.panic_write = part_panic_write;
+
if(master->point && master->unpoint){
slave->mtd.point = part_point;
slave->mtd.unpoint = part_unpoint;