sg_alloc_table_chained() is called by several drivers, but if it is
called before sg_pool_init(), it results in a NULL pointer dereference
in sg_pool_alloc().
Since commit 9b1d6c895002 ("lib: scatterlist: move SG pool code from
SCSI driver to lib/sg_pool.c"), we rely on module_init(sg_pool_init)
is invoked before other module_init calls but this assumption is
fragile.
I slightly changed the link order while Kbuild refactoring Kbuild,
then uncovered this issue. I should keep the current link order, but
depending on a specific call order among module_init is so fragine.
We usually define the init order by specifying *_initcall correctly,
or delay the driver probing by returning -EPROBE_DEFER.
Change module_initcall() to subsys_initcall(), and also delete the
pointless module_exit() because lib/sg_pool.c is always compiled as
built-in. (CONFIG_SG_POOL is bool)
Link: https://lore.kernel.org/all/20220921043946.GA1355561@xxxxxxxxxxxx/
Link: https://lore.kernel.org/all/8e70837d-d859-dfb2-bf7f-83f8b31467bc@xxxxxxxxxxx/
Fixes: 9b1d6c895002 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c")
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
I am sending this to DMA subsystem because I did not find
a corresponding one for lib/sg_pool.c
lib/sg_pool.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)
diff --git a/lib/sg_pool.c b/lib/sg_pool.c
index a0b1a52cd6f7..9bfe60ca3f37 100644
--- a/lib/sg_pool.c
+++ b/lib/sg_pool.c
@@ -1,5 +1,5 @@
// SPDX-License-Identifier: GPL-2.0-only
-#include <linux/module.h>
+#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/slab.h>
@@ -177,16 +177,4 @@ static __init int sg_pool_init(void)
return -ENOMEM;
}
-static __exit void sg_pool_exit(void)
-{
- int i;
-
- for (i = 0; i < SG_MEMPOOL_NR; i++) {
- struct sg_pool *sgp = sg_pools + i;
- mempool_destroy(sgp->pool);
- kmem_cache_destroy(sgp->slab);
- }
-}
-
-module_init(sg_pool_init);
-module_exit(sg_pool_exit);
+subsys_initcall(sg_pool_init);
--
2.34.1
