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Subject[PATCH] fix /proc/partitions oops
If show_partition happens to race with re-reading a partition table
(rescan_partitions), sgp->part[n] can become NULL just after it's been
tested, and so cause an oops: read it once (and read nr_sects just the
once too, to avoid a chance of showing 0).

Signed-off-by: James Cross <james_cross@symantec.com>
---

block/genhd.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

--- 2.6.18-rc6/block/genhd.c.orig 2006-09-07 12:14:32.183218000 +0100
+++ 2.6.18-rc6/block/genhd.c 2006-09-07 12:15:16.134498000 +0100
@@ -261,14 +261,18 @@ static int show_partition(struct seq_fil
(unsigned long long)get_capacity(sgp) >> 1,
disk_name(sgp, 0, buf));
for (n = 0; n < sgp->minors - 1; n++) {
- if (!sgp->part[n])
+ struct hd_struct *partn;
+ unsigned long long nr_sects;
+
+ partn = sgp->part[n];
+ if (!partn)
continue;
- if (sgp->part[n]->nr_sects == 0)
+ nr_sects = partn->nr_sects;
+ if (nr_sects == 0)
continue;
seq_printf(part, "%4d %4d %10llu %s\n",
sgp->major, n + 1 + sgp->first_minor,
- (unsigned long long)sgp->part[n]->nr_sects >> 1 ,
- disk_name(sgp, n + 1, buf));
+ nr_sects >> 1, disk_name(sgp, n + 1, buf));
}

return 0;
-
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