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Message-ID: <56C4A5A2.4010008@redhat.com>
Date: Wed, 17 Feb 2016 17:53:54 +0100
From: Tomas Henzl <thenzl@...hat.com>
To: emilne@...hat.com, Insu Yun <wuninsu@...il.com>
Cc: nagalakshmi.nandigama@...gotech.com,
praveen.krishnamoorthy@...gotech.com,
sreekanth.reddy@...gotech.com, abhijit.mahajan@...gotech.com,
MPT-FusionLinux.pdl@...gotech.com, linux-scsi@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
Taesoo Kim <taesoo@...ech.edu>,
Yeongjin Jang <yeongjin.jang@...ech.edu>,
"Yun, Insu" <insu@...ech.edu>, Changwoo Min <changwoo@...ech.edu>
Subject: Re: [PATCH] fusion-mptbase: handle failed allocation for workqueue
On 16.2.2016 21:52, Ewan Milne wrote:
> On Tue, 2016-02-16 at 13:33 -0500, Insu Yun wrote:
>>
>> On Tue, Feb 16, 2016 at 1:18 PM, Ewan Milne <emilne@...hat.com> wrote:
>> On Mon, 2016-02-15 at 21:50 -0500, Insu Yun wrote:
>> > the failure of ioc->reset_work_q is checked,
>> > but not ioc->fw_event_q.
>> >
>> > Signed-off-by: Insu Yun <wuninsu@...il.com>
>> > ---
>> > drivers/message/fusion/mptbase.c | 7 +++++++
>> > 1 file changed, 7 insertions(+)
>> >
>> > diff --git a/drivers/message/fusion/mptbase.c
>> b/drivers/message/fusion/mptbase.c
>> > index 5dcc031..d4907a1 100644
>> > --- a/drivers/message/fusion/mptbase.c
>> > +++ b/drivers/message/fusion/mptbase.c
>> > @@ -1996,6 +1996,13 @@ mpt_attach(struct pci_dev *pdev,
>> const struct pci_device_id *id)
>> > snprintf(ioc->fw_event_q_name, MPT_KOBJ_NAME_LEN,
>> "mpt/%d", ioc->id);
>> > ioc->fw_event_q =
>> create_singlethread_workqueue(ioc->fw_event_q_name);
>> >
>> > + if (!ioc->fw_event_q) {
>> > + destroy_workqueue(ioc->reset_work_q);
>> > + pci_release_selected_regions(pdev, ioc->bars);
>> > + kfree(ioc);
>> > + return -ENOMEM;
>> > + }
>> > +
>> > if ((r = mpt_do_ioc_recovery(ioc,
>> MPT_HOSTEVENT_IOC_BRINGUP,
>> > CAN_SLEEP)) != 0){
>> > printk(MYIOC_s_ERR_FMT "didn't initialize
>> properly! (%d)\n",
>>
>> This does not look correct to me. The error path for the call
>> to
>> mpt_do_ioc_recovery() after create_singlethread_workqueue()
>> for
>> ioc->fw_event_q does other cleanup, including:
>>
>> list_del(&ioc->list);
>> if (ioc->alt_ioc)
>> ioc->alt_ioc->alt_ioc = NULL;
>> iounmap(ioc->memmap);
>>
>> and
>>
>> kfree(ioc);
>> pci_set_drvdata(pdev, NULL);
>>
>>
>> Oh yes. Right.
>> I just copied from above error handling code.
>>
>>
>>
>>
>> Here I think you are kfree()ing ioc while it is still on the
>> &ioc_list,
>> which will cause a crash.
>>
>> Note to Avago: this code could use a symbolic return code
>> identifier:
>>
>> if (r != -5)
>> pci_release_selected_regions(pdev,
>> ioc->bars);
>>
>>
>> What is -5? it seems strange for me.
>>
>> Is it error code? then it is better to use macro.
> The comments above mpt_do_ioc_recovery() say:
>
> * Returns:
> * 0 for success
> * -1 if failed to get board READY
> * -2 if READY but IOCFacts Failed
> * -3 if READY but PrimeIOCFifos Failed
> * -4 if READY but IOCInit Failed
> * -5 if failed to enable_device and/or request_selected_regions
> * -6 if failed to upload firmware
>
> and yes, it would be better to use a macro (symbolic value) hence my
> comment to Avago.
>>
>>
>> In general, with sequential allocation of resources like this,
>> error
>> handling can be performed using a series of goto's to labels
>> at the
>> end of the function that release the resources in reverse
>> order. This
>> avoids the duplication of code within the function, and
>> reduces the
>> chance for errors when the function is later modified. See
>> init_sd
>> in drivers/scsi/sd.c for an example.
>>
>> Reviewed-by: Ewan D. Milne <emilne@...hat.com>
>>
>>
>>
>>
>> Then in summary, after failing allocation, I need to call
>>
>>
>> list_del(&ioc->list);
>> if (ioc->alt_ioc)
>> ioc->alt_ioc->alt_ioc = NULL;
>> iounmap(ioc->memmap);
>> kfree(ioc);
>> pci_set_drvdata(pdev, NULL);
After 0998d06310 "device-core: Ensure drvdata = NULL when no driver is bound"
the pci_set_drvdata(pdev, NULL); is no more needed.
tomash
>>
>>
>> right?
> I think you also need this:
>
> if (r != -5)
> pci_release_selected_regions(pdev, ioc->bars);
>
> destroy_workqueue(ioc->reset_work_q);
> ioc->reset_work_q = NULL;
>
> prior to your kfree(ioc) call.
>
> Alternatively it looks like the code to create the ioc->fw_event_q could
> be moved up to be right after the code to create the ioc->reset_work_q,
> that might simplify the code a little bit as the ioc has not been added
> to the &ioc_list and pci_set_drvdata() has not yet been called.
>
> Note however that a failed call to mpt_do_ioc_recovery() still needs to
> perform all the recovery actions, including destroying both work queues,
> so consider putting the error handling code at the end of the function
> as I mentioned above. Otherwise, you should add:
>
> destroy_workqueue(ioc->fw_event_q);
> ioc->fw_event_q = NULL;
>
> prior to the call to destroy_workqueue(ioc->reset_work_q) in that path.
>
> -Ewan
>
>>
>> --
>> Regards
>> Insu Yun
>
> --
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