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Revision be14eb619108fa8b7120eb2c42d66d5f623ae10e authored by Brian King on 10 September 2010, 07:03:21 UTC, committed by Jens Axboe on 10 September 2010, 07:03:21 UTC 
block: Range check cpu in blk_cpu_to_group
 
While testing CPU DLPAR, the following problem was discovered.
We were DLPAR removing the first CPU, which in this case was
logical CPUs 0-3. CPUs 0-2 were already marked offline and
we were in the process of offlining CPU 3. After marking
the CPU inactive and offline in cpu_disable, but before the
cpu was completely idle (cpu_die), we ended up in __make_request
on CPU 3. There we looked at the topology map to see which CPU
to complete the I/O on and found no CPUs in the cpu_sibling_map.
This resulted in the block layer setting the completion cpu
to be NR_CPUS, which then caused an oops when we tried to
complete the I/O.

Fix this by sanity checking the value we return from blk_cpu_to_group
to be a valid cpu value.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
1 parent edce682
Raw File
read_write.h 
/*
 * This file is only for sharing some helpers from read_write.c with compat.c.
 * Don't use anywhere else.
 */


typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
typedef ssize_t (*iov_fn_t)(struct kiocb *, const struct iovec *,
		unsigned long, loff_t);

ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
		unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn);
ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
		unsigned long nr_segs, loff_t *ppos, io_fn_t fn);
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