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Message-ID: <32E1700B9017364D9B60AED9960492BC25A7F6FA@fmsmsx120.amr.corp.intel.com>
Date: Mon, 7 Mar 2016 21:17:20 +0000
From: "Marciniszyn, Mike" <mike.marciniszyn@...el.com>
To: nick <xerofoify@...il.com>
CC: "dledford@...hat.com" <dledford@...hat.com>,
"Hefty, Sean" <sean.hefty@...el.com>,
"hal.rosenstock@...il.com" <hal.rosenstock@...il.com>,
"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH RESEND] qib:Fix concurrent access in the function,
qib_init_iba6120_funcs
> From: nick [mailto:xerofoify@...il.com]
> Sent: Monday, March 7, 2016 2:21 PM
> To: Marciniszyn, Mike <mike.marciniszyn@...el.com>
> Cc: dledford@...hat.com; Hefty, Sean <sean.hefty@...el.com>;
> hal.rosenstock@...il.com; linux-rdma@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH RESEND] qib:Fix concurrent access in the function,
> qib_init_iba6120_funcs
>
>
>
> On 2016-03-07 11:34 AM, Marciniszyn, Mike wrote:
> >> This fixes concurrent access in the function, qib_init_iba6120_funcs
> >> by locking around the calls to when setting up f_sendctrl and
> >> f_set_armlauch function pointers to the functions, sendctrl_6120_mod
> >> qib_set_6120_armlaunch due to these functions needing to have their
> >> caller to hold the spinlock that is part of the qib_ibport pointer
> >> they are using and due to the lock not being held by higher up
> >> functions in the caller stack we need to hold it in qib_init_iba6210 to avoid
> conncurrent access when setting up these function pointers.
> >>
> >
> > I'm not sure I agree.
> >
> > static struct pci_driver qib_driver = {
> > .name = QIB_DRV_NAME,
> > .probe = qib_init_one,
> > .remove = qib_remove_one,
> > .id_table = qib_pci_tbl,
> > .err_handler = &qib_pci_err_handler, };
> >
> > The only caller is the probe function, which naturally protects since the device
> cannot be used until the probe returns.
> >
> That's correct my concern was about threads from other kernel contexts but
> then again that's probably me being too conservative about critical region
> protection.
> Cheers,
> Nick
Doug, I'm NAKing this patch based on this reply from Nick.
Given that function vectors cannot be used until the qib_init_iba6120_funcs() functions return, this patch just not needed.
Mike
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