The patch titled
sys_swapon: do not depend on "type" after allocation
has been added to the -mm tree. Its filename is
sys_swapon-do-not-depend-on-type-after-allocation.patch
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------------------------------------------------------
Subject: sys_swapon: do not depend on "type" after allocation
From: Cesar Eduardo Barros <cesarb@xxxxxxxxxx>
Within sys_swapon, after the swap_info entry has been allocated, we
always have type == p->type and swap_info[type] == p. Use this fact to
reduce the dependency on the "type" local variable within the function,
as a preparation to move the allocation of the swap_info entry to a
separate function.
Signed-off-by: Cesar Eduardo Barros <cesarb@xxxxxxxxxx>
Tested-by: Eric B Munson <emunson@xxxxxxxxx>
Acked-by: Eric B Munson <emunson@xxxxxxxxx>
Reviewed-by: Pekka Enberg <penberg@xxxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff -puN mm/swapfile.c~sys_swapon-do-not-depend-on-type-after-allocation mm/swapfile.c
--- a/mm/swapfile.c~sys_swapon-do-not-depend-on-type-after-allocation
+++ a/mm/swapfile.c
@@ -1927,7 +1927,7 @@ SYSCALL_DEFINE2(swapon, const char __use
for (i = 0; i < nr_swapfiles; i++) {
struct swap_info_struct *q = swap_info[i];
- if (i == type || !q->swap_file)
+ if (q == p || !q->swap_file)
continue;
if (mapping == q->swap_file->f_mapping)
goto bad_swap;
@@ -2062,7 +2062,7 @@ SYSCALL_DEFINE2(swapon, const char __use
}
}
- error = swap_cgroup_swapon(type, maxpages);
+ error = swap_cgroup_swapon(p->type, maxpages);
if (error)
goto bad_swap;
@@ -2120,9 +2120,9 @@ SYSCALL_DEFINE2(swapon, const char __use
}
p->next = i;
if (prev < 0)
- swap_list.head = swap_list.next = type;
+ swap_list.head = swap_list.next = p->type;
else
- swap_info[prev]->next = type;
+ swap_info[prev]->next = p->type;
spin_unlock(&swap_lock);
mutex_unlock(&swapon_mutex);
atomic_inc(&proc_poll_event);
@@ -2136,7 +2136,7 @@ bad_swap:
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
}
destroy_swap_extents(p);
- swap_cgroup_swapoff(type);
+ swap_cgroup_swapoff(p->type);
bad_swap_2:
spin_lock(&swap_lock);
p->swap_file = NULL;
_
Patches currently in -mm which might be from cesarb@xxxxxxxxxx are
sys_swapon-use-vzalloc-instead-of-vmalloc-memset.patch
sys_swapon-remove-changelog-from-function-comment.patch
sys_swapon-do-not-depend-on-type-after-allocation.patch
sys_swapon-separate-swap_info-allocation.patch
sys_swapon-simplify-error-return-from-swap_info-allocation.patch
sys_swapon-simplify-error-flow-in-alloc_swap_info.patch
sys_swapon-remove-initial-value-of-name-variable.patch
sys_swapon-move-setting-of-error-nearer-use.patch
sys_swapon-remove-did_down-variable.patch
sys_swapon-remove-bdev-variable.patch
sys_swapon-do-only-cleanup-in-the-cleanup-blocks.patch
sys_swapon-use-a-single-error-label.patch
sys_swapon-separate-bdev-claim-and-inode-lock.patch
sys_swapon-simplify-error-flow-in-claim_swapfile.patch
sys_swapon-move-setting-of-swapfilepages-near-use.patch
sys_swapon-separate-parsing-of-swapfile-header.patch
sys_swapon-simplify-error-flow-in-read_swap_header.patch
sys_swapon-call-swap_cgroup_swapon-earlier.patch
sys_swapon-separate-parsing-of-bad-blocks-and-extents.patch
sys_swapon-simplify-error-flow-in-setup_swap_map_and_extents.patch
sys_swapon-remove-nr_good_pages-variable.patch
sys_swapon-move-printk-outside-lock.patch
sys_swapoff-change-order-to-match-sys_swapon.patch
sys_swapon-separate-final-enabling-of-the-swapfile.patch
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