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: [email protected] Fixes: 99eb1908e643 ("dm switch: factor out switch_region_table_read") Signed-off-by: Haotian Zhang <[email protected]> --- drivers/md/dm-switch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c index 5952f02de1e6..e5b507b4fa7b 100644 --- a/drivers/md/dm-switch.c +++ b/drivers/md/dm-switch.c @@ -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); } /* -- 2.25.1
