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UBI: remove bogus debugging checks

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The 'paranoid_check_empty()' is bogus because, which is easilly
seen on NOR flash, which has long erase cycles, and which may
easilly end-up with half-erased eraseblocks. In this case the
paranoid check fails. I is just wrong to assume that PEBs which
do not have EC headers always contain all 0xFF. Such assumption
should not be made on the I/O level, which is quite low.

Thus, just kill the check.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy 2009-06-29 15:58:36 +03:00
parent 40a71a87fa
commit 1398788fe7
3 changed files with 2 additions and 88 deletions
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1
drivers/mtd/ubi/debug.h
View File

@ -173,6 +173,7 @@ static inline int ubi_dbg_is_erase_failure(void)
#define ubi_dbg_is_bitflip() 0
#define ubi_dbg_is_write_failure() 0
#define ubi_dbg_is_erase_failure() 0
#define ubi_dbg_check_all_ff(ubi, pnum, offset, len) 0
#endif /* !CONFIG_MTD_UBI_DEBUG */
#endif /* !__UBI_DEBUG_H__ */

87
drivers/mtd/ubi/io.c
View File

@ -98,14 +98,12 @@ static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum);
static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
const struct ubi_vid_hdr *vid_hdr);
static int paranoid_check_empty(struct ubi_device *ubi, int pnum);
#else
#define paranoid_check_not_bad(ubi, pnum) 0
#define paranoid_check_peb_ec_hdr(ubi, pnum) 0
#define paranoid_check_ec_hdr(ubi, pnum, ec_hdr) 0
#define paranoid_check_peb_vid_hdr(ubi, pnum) 0
#define paranoid_check_vid_hdr(ubi, pnum, vid_hdr) 0
#define paranoid_check_empty(ubi, pnum) 0
#endif
/**
@ -669,10 +667,6 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
if (read_err != -EBADMSG &&
check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
/* The physical eraseblock is supposedly empty */
err = ubi_dbg_check_all_ff(ubi, pnum, 0, ubi->peb_size);
if (err)
return err > 0 ? UBI_IO_BAD_EC_HDR : err;
if (verbose)
ubi_warn("no EC header found at PEB %d, "
"only 0xFF bytes", pnum);
@ -943,15 +937,6 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
if (read_err != -EBADMSG &&
check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
/* The physical eraseblock is supposedly free */
/*
* The below is just a paranoid check, it has to be
* compiled out if paranoid checks are disabled.
*/
err = paranoid_check_empty(ubi, pnum);
if (err)
return err > 0 ? UBI_IO_BAD_VID_HDR : err;
if (verbose)
ubi_warn("no VID header found at PEB %d, "
"only 0xFF bytes", pnum);
@ -1241,8 +1226,6 @@ int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
int err;
loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
ubi_assert(!mutex_is_locked(&ubi->dbg_buf_mutex));
mutex_lock(&ubi->dbg_buf_mutex);
err = ubi->mtd->read(ubi->mtd, addr, len, &read, ubi->dbg_peb_buf);
if (err && err != -EUCLEAN) {
@ -1273,74 +1256,4 @@ error:
return err;
}
/**
* paranoid_check_empty - whether a PEB is empty.
* @ubi: UBI device description object
* @pnum: the physical eraseblock number to check
*
* This function makes sure PEB @pnum is empty, which means it contains only
* %0xFF data bytes. Returns zero if the PEB is empty, %1 if not, and a
* negative error code in case of failure.
*
* Empty PEBs have the EC header, and do not have the VID header. The caller of
* this function should have already made sure the PEB does not have the VID
* header. However, this function re-checks that, because it is possible that
* the header and data has already been written to the PEB.
*
* Let's consider a possible scenario. Suppose there are 2 tasks - A and B.
* Task A is in 'wear_leveling_worker()'. It is reading VID header of PEB X to
* find which LEB it corresponds to. PEB X is currently unmapped, and has no
* VID header. Task B is trying to write to PEB X.
*
* Task A: in 'ubi_io_read_vid_hdr()': reads the VID header from PEB X. The
* read data contain all 0xFF bytes;
* Task B: writes VID header and some data to PEB X;
* Task A: assumes PEB X is empty, calls 'paranoid_check_empty()'. And if we
* do not re-read the VID header, and do not cancel the checking if it
* is there, we fail.
*/
static int paranoid_check_empty(struct ubi_device *ubi, int pnum)
{
int err, offs = ubi->vid_hdr_aloffset, len = ubi->vid_hdr_alsize;
size_t read;
uint32_t magic;
const struct ubi_vid_hdr *vid_hdr;
mutex_lock(&ubi->dbg_buf_mutex);
err = ubi->mtd->read(ubi->mtd, offs, len, &read, ubi->dbg_peb_buf);
if (err && err != -EUCLEAN) {
ubi_err("error %d while reading %d bytes from PEB %d:%d, "
"read %zd bytes", err, len, pnum, offs, read);
goto error;
}
vid_hdr = ubi->dbg_peb_buf;
magic = be32_to_cpu(vid_hdr->magic);
if (magic == UBI_VID_HDR_MAGIC)
/* The PEB contains VID header, so it is not empty */
goto out;
err = check_pattern(ubi->dbg_peb_buf, 0xFF, len);
if (err == 0) {
ubi_err("flash region at PEB %d:%d, length %d does not "
"contain all 0xFF bytes", pnum, offs, len);
goto fail;
}
out:
mutex_unlock(&ubi->dbg_buf_mutex);
return 0;
fail:
ubi_err("paranoid check failed for PEB %d", pnum);
ubi_msg("hex dump of the %d-%d region", offs, offs + len);
print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
ubi->dbg_peb_buf, len, 1);
err = 1;
error:
ubi_dbg_dump_stack();
mutex_unlock(&ubi->dbg_buf_mutex);
return err;
}
#endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */

2
drivers/mtd/ubi/wl.c
View File

@ -463,7 +463,7 @@ retry:
err = ubi_dbg_check_all_ff(ubi, e->pnum, ubi->vid_hdr_aloffset,
ubi->peb_size - ubi->vid_hdr_aloffset);
if (err) {
dbg_err("new PEB does not contain all 0xFF bytes");
ubi_err("new PEB %d does not contain all 0xFF bytes", e->pnum);
return err > 0 ? -EINVAL : err;
}