diff options
author | Christian Riesch <christian.riesch@omicron.at> | 2014-03-06 06:42:37 -0500 |
---|---|---|
committer | Brian Norris <computersforpeace@gmail.com> | 2014-03-11 01:42:31 -0400 |
commit | 9a78bc83b4c31f67202b7b0a77fa25da732f44a3 (patch) | |
tree | 386d354b6cba9a22eca92c07ab10206c476c955a /drivers/mtd/mtdchar.c | |
parent | ea6d833a3fddcd1d60414d48f34c7f4fbe88608f (diff) |
mtd: Fix the behavior of OTP write if there is not enough room for data
If a write to one time programmable memory (OTP) hits the end of this
memory area, no more data can be written. The count variable in
mtdchar_write() in drivers/mtd/mtdchar.c is not decreased anymore.
We are trapped in the loop forever, mtdchar_write() will never return
in this case.
The desired behavior of a write in such a case is described in [1]:
- Try to write as much data as possible, truncate the write to fit into
the available memory and return the number of bytes that actually
have been written.
- If no data could be written at all, return -ENOSPC.
This patch fixes the behavior of OTP write if there is not enough space
for all data:
1) mtd_write_user_prot_reg() in drivers/mtd/mtdcore.c is modified to
return -ENOSPC if no data could be written at all.
2) mtdchar_write() is modified to handle -ENOSPC correctly. Exit if a
write returned -ENOSPC and yield the correct return value, either
then number of bytes that could be written, or -ENOSPC, if no data
could be written at all.
Furthermore the patch harmonizes the behavior of the OTP memory write
in drivers/mtd/devices/mtd_dataflash.c with the other implementations
and the requirements from [1]. Instead of returning -EINVAL if the data
does not fit into the OTP memory, we try to write as much data as
possible/truncate the write.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html
Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'drivers/mtd/mtdchar.c')
-rw-r--r-- | drivers/mtd/mtdchar.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c index 250798cf76aa..7d4e7b9da3a1 100644 --- a/drivers/mtd/mtdchar.c +++ b/drivers/mtd/mtdchar.c | |||
@@ -324,6 +324,15 @@ static ssize_t mtdchar_write(struct file *file, const char __user *buf, size_t c | |||
324 | default: | 324 | default: |
325 | ret = mtd_write(mtd, *ppos, len, &retlen, kbuf); | 325 | ret = mtd_write(mtd, *ppos, len, &retlen, kbuf); |
326 | } | 326 | } |
327 | |||
328 | /* | ||
329 | * Return -ENOSPC only if no data could be written at all. | ||
330 | * Otherwise just return the number of bytes that actually | ||
331 | * have been written. | ||
332 | */ | ||
333 | if ((ret == -ENOSPC) && (total_retlen)) | ||
334 | break; | ||
335 | |||
327 | if (!ret) { | 336 | if (!ret) { |
328 | *ppos += retlen; | 337 | *ppos += retlen; |
329 | total_retlen += retlen; | 338 | total_retlen += retlen; |