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author | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2009-05-12 15:43:44 +0300 |
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committer | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2009-05-18 12:28:25 +0300 |
commit | ffb6b7e4fdef715061859651fe46cd27afc6acec (patch) | |
tree | 7b01298488f897b1176fc405fa8b4813f50ebf7b /drivers/mtd/ubi/Kconfig.debug | |
parent | 2cb81e218f336dc5438a960d1ae098188db9ff11 (diff) |
UBI: fix races in I/O debugging checks
When paranoid checs are enabled, the 'io_paral' test from the
'mtd-utils' package fails. The symptoms are:
UBI error: paranoid_check_all_ff: flash region at PEB 3973:512, length 15872 does not contain all 0xFF bytes
UBI error: paranoid_check_all_ff: paranoid check failed for PEB 3973
UBI: hex dump of the 512-16384 region
It turned out to be a bug in the checking function. Suppose there
are 2 tasks - A and B. Task A is the wear-levelling working
('wear_leveling_worker()'). It is reading the VID header to find
which LEB this PEB belongs to. Say, task A is reading header
of PEB X. Suppose PEB X is 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_all_ff()', which
fails.
The solution for this problem is to make 'paranoid_check_all_ff()'
re-read the VID header, re-check it, and only if it is not there,
check the rest. This now implemented by the 'paranoid_check_empty()'
function.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Diffstat (limited to 'drivers/mtd/ubi/Kconfig.debug')
0 files changed, 0 insertions, 0 deletions