[PATCH net v2] net: ipa: balance runtime PM reference on remove error

[PATCH net v2] net: ipa: balance runtime PM reference on remove error

[Ruoyu Wang]

ipa_remove() takes a runtime PM reference before accessing IPA hardware
during teardown. If a concurrent modem start or stop keeps
ipa_modem_stop() busy across both attempts, the callback intentionally
returns without releasing the remaining resources because proceeding
with teardown could crash. That return also skips the matching
pm_runtime_put_noidle(), leaving the callback's usage-count reference
held.

Drop only this runtime PM reference before returning.
pm_runtime_put_noidle() does not request an idle transition, so the
hardware and resources retained on this exceptional path remain
untouched while the usage count stays balanced.

This issue was found by a static analysis checker and confirmed by
manual source review.

Fixes: 923a6b698447 ("net: ipa: get clock in ipa_probe()")
Assisted-by: unnamed:gpt-5.5 typestate
Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
Reviewed-by: Alex Elder <elder@riscstar.com>

---
Changes in v2:
- Simplify the teardown comment as requested.
- Add the Assisted-by tag.

v1: https://lore.kernel.org/r/20260814134047.1387177-1-ruoyuw560@gmail.com/
---
 drivers/net/ipa/ipa_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 788dd99af2a4dc..8d82fd5bb24b97 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -969,12 +969,12 @@ static void ipa_remove(struct platform_device *pdev)
 		}
 		if (ret) {
 			/*
-			 * Not cleaning up here properly might also yield a
-			 * crash later on. As the device is still unregistered
-			 * in this case, this might even yield a crash later on.
+			 * Continuing teardown after failing to stop the modem
+			 * could crash, so leave the remaining resources allocated.
 			 */
 			dev_err(dev, "Failed to stop modem (%pe), leaking resources\n",
 				ERR_PTR(ret));
+			pm_runtime_put_noidle(dev);
 			return;
 		}
 
-- 
2.51.0

Re: [PATCH net v2] net: ipa: balance runtime PM reference on remove error

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sat, 15 Aug 2026 23:17:37 +0800 you wrote:
> ipa_remove() takes a runtime PM reference before accessing IPA hardware
> during teardown. If a concurrent modem start or stop keeps
> ipa_modem_stop() busy across both attempts, the callback intentionally
> returns without releasing the remaining resources because proceeding
> with teardown could crash. That return also skips the matching
> pm_runtime_put_noidle(), leaving the callback's usage-count reference
> held.
> 
> [...]

Here is the summary with links:
  - [net,v2] net: ipa: balance runtime PM reference on remove error
    https://git.kernel.org/netdev/net/c/6b9eaa61ff2d

You are awesome, thank you!
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