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authorRichard Purdie <rpurdie@rpsys.net>2008-02-06 05:17:15 -0500
committerDavid Woodhouse <dwmw2@infradead.org>2008-02-07 05:30:48 -0500
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 6174a97d7902..c66902df3171 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,
151 len, retlen, buf); 151 len, retlen, buf);
152} 152}
153 153
154static int part_panic_write (struct mtd_info *mtd, loff_t to, size_t len,
155 size_t *retlen, const u_char *buf)
156{
157 struct mtd_part *part = PART(mtd);
158 if (!(mtd->flags & MTD_WRITEABLE))
159 return -EROFS;
160 if (to >= mtd->size)
161 len = 0;
162 else if (to + len > mtd->size)
163 len = mtd->size - to;
164 return part->master->panic_write (part->master, to + part->offset,
165 len, retlen, buf);
166}
167
154static int part_write_oob(struct mtd_info *mtd, loff_t to, 168static int part_write_oob(struct mtd_info *mtd, loff_t to,
155 struct mtd_oob_ops *ops) 169 struct mtd_oob_ops *ops)
156{ 170{
@@ -352,6 +366,9 @@ int add_mtd_partitions(struct mtd_info *master,
352 slave->mtd.read = part_read; 366 slave->mtd.read = part_read;
353 slave->mtd.write = part_write; 367 slave->mtd.write = part_write;
354 368
369 if (master->panic_write)
370 slave->mtd.panic_write = part_panic_write;
371
355 if(master->point && master->unpoint){ 372 if(master->point && master->unpoint){
356 slave->mtd.point = part_point; 373 slave->mtd.point = part_point;
357 slave->mtd.unpoint = part_unpoint; 374 slave->mtd.unpoint = part_unpoint;