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net: ibm: emac: mal: fix potential system hang in mal_remove()

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napi_disable() is not idempotent and calling it on an already-disabled
or unenabled NAPI context will cause the kernel to spin indefinitely
waiting for the NAPI_STATE_SCHED bit to clear.

In mal_remove(), napi_disable() is called unconditionally. If no MACs were
registered, NAPI was never enabled. Also, if they were registered but
subsequently unregistered, NAPI was already disabled in
mal_unregister_commac(). In either case, calling napi_disable() causes
the kernel to hang upon module removal.

Fix this by only calling napi_disable() in mal_remove() if the commac list
is not empty (which implies NAPI is enabled).

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://patch.msgid.link/20260603230821.5619-1-rosenp@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Rosen Penev 2026-06-03 16:08:21 -07:00 committed by Jakub Kicinski
parent f0ba7f385d
commit 7c5d41f87f
1 changed files with 3 additions and 3 deletions
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6
drivers/net/ethernet/ibm/emac/mal.c
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@ -712,13 +712,13 @@ static void mal_remove(struct platform_device *ofdev)
MAL_DBG(mal, "remove" NL);
/* Synchronize with scheduled polling */
napi_disable(&mal->napi);
if (!list_empty(&mal->list))
if (!list_empty(&mal->list)) {
napi_disable(&mal->napi);
/* This is *very* bad */
WARN(1, KERN_EMERG
"mal%d: commac list is not empty on remove!\n",
mal->index);
}
mal_reset(mal);