Hi Vladimir & Julian The driver is still moving to the Linux driver and also its being changed. Your patch is everything's ok. I also agree to Julian review. Thanks, BR Leo -----Original Message----- From: Vladimir Zapolskiy [mailto:vz@xxxxxxxxx] Sent: Thursday, March 10, 2016 9:36 AM To: Julian Calaby <julian.calaby@xxxxxxxxx> Cc: Lee, Glen <Glen.Lee@xxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Kim, Johnny <johnny.kim@xxxxxxxxx>; Shin, Austin <Austin.Shin@xxxxxxxxx>; Park, Chris <Chris.Park@xxxxxxxxx>; Cho, Tony <Tony.Cho@xxxxxxxxx>; Kim, Leo <Leo.Kim@xxxxxxxxx>; linux-wireless <linux-wireless@xxxxxxxxxxxxxxx>; devel@xxxxxxxxxxxxxxxxxxxx Subject: Re: [PATCH] staging: wilc1000: fix check of kthread_run() return value Hi Julian, On 10.03.2016 02:24, Julian Calaby wrote: > Hi Vladimir, > > On Thu, Mar 10, 2016 at 11:02 AM, Vladimir Zapolskiy <vz@xxxxxxxxx> wrote: >> Hi Julian, >> >> On 10.03.2016 01:42, Julian Calaby wrote: >>> Hi Vladimir, >>> >>> On Thu, Mar 10, 2016 at 10:30 AM, Vladimir Zapolskiy <vz@xxxxxxxxx> wrote: >>>> Hi Julian, >>>> >>>> On 10.03.2016 01:27, Julian Calaby wrote: >>>>> Hi Vladimir, >>>>> >>>>> On Thu, Mar 10, 2016 at 10:13 AM, Vladimir Zapolskiy <vz@xxxxxxxxx> wrote: >>>>>> The kthread_run() function returns either a valid task_struct or >>>>>> ERR_PTR() value, check for NULL is invalid. The change fixes >>>>>> potential oops, e.g. in OOM situation. >>>>>> >>>>>> Signed-off-by: Vladimir Zapolskiy <vz@xxxxxxxxx> >>>>>> --- >>>>>> drivers/staging/wilc1000/linux_wlan.c | 4 ++-- >>>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>>> >>>>>> diff --git a/drivers/staging/wilc1000/linux_wlan.c >>>>>> b/drivers/staging/wilc1000/linux_wlan.c >>>>>> index 54fe9d7..5077c30 100644 >>>>>> --- a/drivers/staging/wilc1000/linux_wlan.c >>>>>> +++ b/drivers/staging/wilc1000/linux_wlan.c >>>>>> @@ -849,10 +849,10 @@ static int wlan_initialize_threads(struct net_device *dev) >>>>>> PRINT_D(INIT_DBG, "Creating kthread for transmission\n"); >>>>>> wilc->txq_thread = kthread_run(linux_wlan_txq_task, (void *)dev, >>>>>> "K_TXQ_TASK"); >>>>>> - if (!wilc->txq_thread) { >>>>>> + if (IS_ERR(wilc->txq_thread)) { >>>>>> PRINT_ER("couldn't create TXQ thread\n"); >>>>>> wilc->close = 0; >>>>>> - return -ENOBUFS; >>>>>> + return PTR_ERR(wilc->txq_thread); >>>>> >>>>> Are you sure changing the error returned is correct? Do all the >>>>> callers of wlan_initialize_threads() handle the full range of >>>>> errors from kthread_run()? >>>> >>>> Have you checked the driver? >>> >>> I'm making sure you have. It's possible that there's a good reason >>> why this returns -ENOBUFS I want to know that you've at least >>> considered that possibility. >> >> You have my confirmation, I've checked the call stack before >> publishing this fix. > > Awesome. > >>>> This function is called once on initialization, the check on the >>>> upper layer has "if (ret < 0) goto exit_badly;" form. >>> >>> And practically everything in the chain up to net_device_ops uses >>> the same error handling scheme so it's probably fine. >> >> dev_open() >> __dev_open() >> wilc_mac_open() >> wilc1000_wlan_init() >> wlan_initialize_threads() >> >> Oh, why kernel threads within a driver are init'ed/destroyed on each >> device up/down state transition? > > You'll have to ask the driver developers. I believe this was a cross > platform driver that is currently being Linux-ised, so I'm guessing > this is some artefact of that. > >>> You should also document this change in the commit message. >> >> The change is documented in the commit message, take a look. But I >> didn't add "I swear it does not break anything" ;) > > You > 1. corrected the test in the if statement 2. changed the return value > from -ENOBUFS in your patch, however you only documented the first > part. Agree, it makes sense. > I would have expected a commit message along the lines of: > > ---->8---- > > The kthread_run() function returns either a valid task_struct or > ERR_PTR() value, so the check for NULL is invalid. > > Also return the error from kthread_run() instead of -ENOBUFS. > > ----8<---- > Before publishing v2 let see if driver maintainers have something else to add, or may be it is better to preserve -ENOBUFS, or may be they are so kind to update the commit message on patch application. Julian, thanks for review. -- With best wishes, Vladimir ��.n��������+%������w��{.n�����{���zW����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
