[PATCH] spi: mt65xx: make sure operations completed before unloading

[Daniel Golle <daniel@makrotopia.org>]

When unloading the spi-mt65xx kernel module during an ongoing spi-mem
operation the kernel will Oops shortly after unloading the module.
This is because wait_for_completion_timeout was still running and
returning into the no longer loaded module:

Internal error: Oops: 0000000096000005 [#1] SMP
Modules linked in: [many, but spi-mt65xx is no longer there]
CPU: 0 PID: 2578 Comm: block Tainted: G        W  O       6.3.0-next-20230428+ #0
Hardware name: Bananapi BPI-R3 (DT)
pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __lock_acquire+0x18c/0x20e8
lr : __lock_acquire+0x9b8/0x20e8
sp : ffffffc009ec3400
x29: ffffffc009ec3400 x28: 0000000000000001 x27: 0000000000000004
x26: ffffff80082888c8 x25: 0000000000000000 x24: 0000000000000000
x23: ffffffc009609da8 x22: ffffff8008288000 x21: ffffff8008288968
x20: 00000000000003c2 x19: ffffff8008be7990 x18: 00000000000002af
x17: 0000000000000000 x16: 0000000000000000 x15: ffffffc008d78970
x14: 000000000000080d x13: 00000000000002af x12: 00000000ffffffea
x11: 00000000ffffefff x10: ffffffc008dd0970 x9 : ffffffc008d78918
x8 : 0000000000017fe8 x7 : 0000000000000001 x6 : 0000000000000000
x5 : ffffff807fb53910 x4 : 0000000000000000 x3 : 0000000000000027
x2 : 0000000000000027 x1 : 0000000000000000 x0 : 00000000000c03c2
Call trace:
 __lock_acquire+0x18c/0x20e8
 lock_acquire+0x100/0x2a4
 _raw_spin_lock_irq+0x58/0x74
 __wait_for_common+0xe0/0x1b4
 wait_for_completion_timeout+0x1c/0x24
 0xffffffc000acc8a4 <--- used to be mtk_spi_transfer_wait
 spi_mem_exec_op+0x390/0x3ec
 spi_mem_no_dirmap_read+0x6c/0x88
 spi_mem_dirmap_read+0xcc/0x12c
 spinand_read_page+0xf8/0x1dc
 spinand_mtd_read+0x1b4/0x2fc
 mtd_read_oob_std+0x58/0x7c
 mtd_read_oob+0x8c/0x148
 mtd_read+0x50/0x6c
 ...

Prevent this by completing in mtk_spi_remove if needed.

Fixes: 9f763fd20da7 ("spi: mediatek: add spi memory support for ipm design")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---

A short grep revealed that many if not most other SPI drivers may need
the same fix. However, I can impossibly test all of them, so let's
start with this one.

 drivers/spi/spi-mt65xx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 21c321f437667..d7432e2219d85 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -1275,6 +1275,9 @@ static int mtk_spi_remove(struct platform_device *pdev)
 	struct mtk_spi *mdata = spi_master_get_devdata(master);
 	int ret;
 
+	if (mdata->use_spimem && !completion_done(&mdata->spimem_done))
+		complete(&mdata->spimem_done);
+
 	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret < 0)
 		return ret;
-- 
2.40.1