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dm-switch: use WRITE_ONCE() in switch_region_table_write()

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switch_region_table_read() accesses the region table with READ_ONCE()
and is called from the lockless switch_map() IO path. However,
switch_region_table_write() stores to the same array with a plain
assignment. This results in an inconsistent access pattern for a
lockless shared variable and may trigger data race reports.

Use WRITE_ONCE() to pair with the existing READ_ONCE() in
switch_region_table_read().

Cc: stable@vger.kernel.org
Fixes: 99eb1908e6 ("dm switch: factor out switch_region_table_read")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Haotian Zhang
2026-07-11 22:21:55 +08:00
committed by Mikulas Patocka
parent 00211ede62
commit c7391ebe33
1 changed files with 1 additions and 1 deletions
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2
drivers/md/dm-switch.c
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@@ -184,7 +184,7 @@ static void switch_region_table_write(struct switch_ctx *sctx, unsigned long reg
pte = sctx->region_table[region_index];
pte &= ~((((region_table_slot_t)1 << sctx->region_table_entry_bits) - 1) << bit);
pte |= (region_table_slot_t)value << bit;
sctx->region_table[region_index] = pte;
WRITE_ONCE(sctx->region_table[region_index], pte);
}
/*