Messages in this thread | | | Date | Sun, 18 Mar 2001 22:35:58 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH] off-by-1 error in ide-probe (2.4.x) |
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On Sun, Mar 18 2001, Paul Gortmaker wrote: > There is a potentially serious bug in ide-probe.c in which max_sectors > is set to 256 instead of 255. I am surprised that this hasn't bit anyone > else yet. Perhaps because you need a disk that is slow in comparison to > the host in order for the queue to climb up to and then hit the 256, at > which point it then falls over.
You don't need a slow disk, it's trivial to provoke 256 sector sized request on even the fastest disk available. People hit it all the time, just with working drives...
> For example, with an old 700MB Maxtor on a "fast" 486, VL-bus, PIO, > hdparm -c1 -m8 -u1, I could pretty much on demand generate the following > error by multiple builds, or by the final linking of any big project:
The 256 is _not_ a bug in the driver, it's more likely a bug in your drive. 256 is a perfectly legal transfer size. That said, maybe it is a good idea to leave it at 255 just for safety on drives not handling 0 sectors == 128kB transfer.
-- Jens Axboe
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