lib/sg_pool: change module_init(sg_pool_init) to subsys_initcall

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 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 fragile.

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/[email protected]/
Link: https://lore.kernel.org/all/[email protected]/
Fixes: 9b1d6c895002 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c")
Reported-by: Guenter Roeck <[email protected]>
Reported-by: Marek Szyprowski <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Robin Murphy <[email protected]>
Tested-by: Marek Szyprowski <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>

0 files changed, 0 insertions, 0 deletions