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authorBodo Stroesser <bostroesser@gmail.com>2022-05-17 22:29:13 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2022-05-20 03:16:27 +0300
commit325d5c5fb216674296f3902a8902b942da3adc5b (patch)
tree98cee22612befcbff95316d83366e73fc4e6ecd2 /drivers
parentd627660c22b51121262c03dfa1a51bf54361f5a9 (diff)
downloadlinux-325d5c5fb216674296f3902a8902b942da3adc5b.tar.xz
scsi: target: tcmu: Avoid holding XArray lock when calling lock_page
In tcmu_blocks_release(), lock_page() is called to prevent a race causing possible data corruption. Since lock_page() might sleep, calling it while holding XArray lock is a bug. To fix this, replace the xas_for_each() call with xa_for_each_range(). Since the latter does its own handling of XArray locking, the xas_lock() and xas_unlock() calls around the original loop are no longer necessary. The switch to xa_for_each_range() slows down the loop slightly. This is acceptable since tcmu_blocks_release() is not relevant for performance. Link: https://lore.kernel.org/r/20220517192913.21405-1-bostroesser@gmail.com Fixes: bb9b9eb0ae2e ("scsi: target: tcmu: Fix possible data corruption") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Bodo Stroesser <bostroesser@gmail.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/target/target_core_user.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index b1fd06edea59..3deaeecb712e 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -1661,13 +1661,14 @@ static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd)
static u32 tcmu_blocks_release(struct tcmu_dev *udev, unsigned long first,
unsigned long last)
{
- XA_STATE(xas, &udev->data_pages, first * udev->data_pages_per_blk);
struct page *page;
+ unsigned long dpi;
u32 pages_freed = 0;
- xas_lock(&xas);
- xas_for_each(&xas, page, (last + 1) * udev->data_pages_per_blk - 1) {
- xas_store(&xas, NULL);
+ first = first * udev->data_pages_per_blk;
+ last = (last + 1) * udev->data_pages_per_blk - 1;
+ xa_for_each_range(&udev->data_pages, dpi, page, first, last) {
+ xa_erase(&udev->data_pages, dpi);
/*
* While reaching here there may be page faults occurring on
* the to-be-released pages. A race condition may occur if
@@ -1691,7 +1692,6 @@ static u32 tcmu_blocks_release(struct tcmu_dev *udev, unsigned long first,
__free_page(page);
pages_freed++;
}
- xas_unlock(&xas);
atomic_sub(pages_freed, &global_page_count);