From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e24smtp05.br.ibm.com (e24smtp05.br.ibm.com [32.104.18.26]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id E84E02C0089 for ; Sat, 1 Feb 2014 04:25:12 +1100 (EST) Received: from /spool/local by e24smtp05.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 31 Jan 2014 15:25:04 -0200 Received: from d24relay03.br.ibm.com (d24relay03.br.ibm.com [9.13.184.25]) by d24dlp01.br.ibm.com (Postfix) with ESMTP id 054373520064 for ; Fri, 31 Jan 2014 12:24:59 -0500 (EST) Received: from d24av02.br.ibm.com (d24av02.br.ibm.com [9.8.31.93]) by d24relay03.br.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s0VHOPhR36897010 for ; Fri, 31 Jan 2014 15:24:26 -0200 Received: from d24av02.br.ibm.com (localhost [127.0.0.1]) by d24av02.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s0VHOxdv007521 for ; Fri, 31 Jan 2014 15:24:59 -0200 Date: Fri, 31 Jan 2014 15:24:58 -0200 From: Thadeu Lima de Souza Cascardo To: Gavin Shan Subject: Re: [PATCH] powerpc/eeh: drop taken reference to driver on eeh_rmv_device Message-ID: <20140131172458.GA2039@oc0268524204.ibm.com> References: <1391086848-11311-1-git-send-email-cascardo@linux.vnet.ibm.com> <20140131004611.GA6790@shangw.(null)> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20140131004611.GA6790@shangw.(null)> Cc: linuxppc-dev@lists.ozlabs.org, paulus@samba.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Jan 31, 2014 at 08:46:11AM +0800, Gavin Shan wrote: > 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 > >--- > > 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(). You are right, we need to call it before we call pci_stop_and_remove_bus_device, otherwise dev->driver will be NULL, and eeh_pcid_put will not do module_put. On the other hand, we could change the call to eeh_pcid_put to accept struct pci_driver instead. > > > 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. > What if try_module_get returned false on eeh_pcid_get? How about something like the patch below? > > } > > > > Thanks, > Gavin --- diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c index 7bb30dc..3a397fa 100644 --- a/arch/powerpc/kernel/eeh_driver.c +++ b/arch/powerpc/kernel/eeh_driver.c @@ -352,6 +352,7 @@ static void *eeh_rmv_device(void *data, void *userdata) struct eeh_dev *edev = (struct eeh_dev *)data; struct pci_dev *dev = eeh_dev_to_pci_dev(edev); int *removed = (int *)userdata; + bool has_err_handler; /* * Actually, we should remove the PCI bridges as well. @@ -362,8 +363,12 @@ static void *eeh_rmv_device(void *data, void *userdata) */ if (!dev || (dev->hdr_type & PCI_HEADER_TYPE_BRIDGE)) return NULL; + driver = eeh_pcid_get(dev); - if (driver && driver->err_handler) + has_err_handler = driver && driver->err_handler; + if (driver) + eeh_pcid_put(dev); + if (has_err_handler) return NULL; /* Remove it from PCI subsystem */ ---