[PATCH] mmc: omap: synchronize clock timer before disabling fclk

[Runyu Xiao]

mmc_omap_select_slot() removes clk_timer with timer_delete() before
switching slots and changing the functional clock state.  timer_delete()
only removes a pending timer and does not wait for a callback that is
already running.

If mmc_omap_clk_timer() is already running, it can therefore call
mmc_omap_fclk_enable() while the request or slot-switch path changes the
same clock state.  During host removal, the same window can overlap the
final clock shutdown.

Use timer_delete_sync() so the callback has completed before slot switching
or changing the functional clock state.  Keep the timer restartable for
normal request handling.

Fixes: 0807a9b5739a ("MMC: OMAP: Lazy clock shutdown")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: LLM
Signed-off-by: Runyu Xiao <runyu.xiao@xxxxxxxxxx>
---
 drivers/mmc/host/omap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index 527b89a5e..02d288e4e 100644
--- a/drivers/mmc/host/omap.c
+++ b/drivers/mmc/host/omap.c
@@ -214,7 +214,7 @@ static void mmc_omap_select_slot(struct mmc_omap_slot *slot, int claimed)
 	host->mmc = slot->mmc;
 	spin_unlock_irqrestore(&host->slot_lock, flags);
 no_claim:
-	timer_delete(&host->clk_timer);
+	timer_delete_sync(&host->clk_timer);
 	if (host->current_slot != slot || !claimed)
 		mmc_omap_fclk_offdelay(host->current_slot);
 
@@ -273,7 +273,7 @@ static void mmc_omap_release_slot(struct mmc_omap_slot *slot, int clk_enabled)
 		/* Keeps clock running for at least 8 cycles on valid freq */
 		mod_timer(&host->clk_timer, jiffies  + HZ/10);
 	else {
-		timer_delete(&host->clk_timer);
+		timer_delete_sync(&host->clk_timer);
 		mmc_omap_fclk_offdelay(slot);
 		mmc_omap_fclk_enable(host, 0);
 	}
-- 
2.34.1