Subject: Re: [PATCH] powerpc/eeh: drop taken reference to driver on eeh_rmv_device

From: Gavin Shan <[email-masked]>
Date: Fri, 31 Jan 2014 08:46:11 +0800

On Thu, Jan 30, 2014 at 11:00:48AM -0200, Thadeu Lima de Souza Cascardo wrote:
>Commit f5c57710dd62dd06f176934a8b4b8accbf00f9f8 ("powerpc/eeh: Use
>partial hotplug for EEH unaware drivers") introduces eeh_rmv_device,
>which may grab a reference to a driver, but not release it.
>
>That prevents a driver from being removed after it has gone through EEH
>recovery.
>
>This patch drops the reference in either exit path if it was taken.
>
>Signed-off-by: Thadeu Lima de Souza Cascardo <[email-masked]>
>---
> arch/powerpc/kernel/eeh_driver.c |    5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
>diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
>index 7bb30dc..afe7337 100644
>--- a/arch/powerpc/kernel/eeh_driver.c
>+++ b/arch/powerpc/kernel/eeh_driver.c
>@@ -364,7 +364,7 @@ static void *eeh_rmv_device(void *data, void *userdata)
> 		return NULL;
> 	driver = eeh_pcid_get(dev);
> 	if (driver && driver->err_handler)
>-		return NULL;
>+		goto out;
>
> 	/* Remove it from PCI subsystem */
> 	pr_debug("EEH: Removing %s without EEH sensitive driver\n",
>@@ -377,6 +377,9 @@ static void *eeh_rmv_device(void *data, void *userdata)

For normal case (driver without EEH support), we probably release the reference
to the driver before pci_stop_and_remove_bus_device().

> 	pci_stop_and_remove_bus_device(dev);
> 	pci_unlock_rescan_remove();
>
>+out:
>+	if (driver)
>+		eeh_pcid_put(dev);
> 	return NULL;

We needn't "if (driver)" here as eeh_pcid_put() already had the check.

> }

Thanks,
Gavin