From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
To: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Julian Calaby <julian.calaby@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>
Subject: Re: [PATCHv4 3/4] sparc64: Avoid irqsave/restore on vio.lock if in_softirq()
Date: Wed, 22 Oct 2014 00:16:12 +0000 [thread overview]
Message-ID: <20141022001612.GB26724@oracle.com> (raw)
In-Reply-To: <5446F291.1030400@oracle.com>
On (10/21/14 18:56), Dave Kleikamp wrote:
> >
> > Is gcc not smart enough to know that this variable isn't used before
> > it's set? (I assume it isn't used elsewhere in this function)
>
> It probably assumes in_softirq() might evaluate differently in the each
> case.
yes, that's what I suspected too. I suppose it is possible
from the compiler's point of view that something in between
might change the result of in_softirq() so that we may be
using an uninit variable in the second call.
anyway, the warning was annoying, and would only numb the
user into ignoring other real issues, so I figured I might
as well silence the warning.
--Sowmini
WARNING: multiple messages have this Message-ID (diff)
From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
To: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Julian Calaby <julian.calaby@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>
Subject: Re: [PATCHv4 3/4] sparc64: Avoid irqsave/restore on vio.lock if in_softirq()
Date: Tue, 21 Oct 2014 20:16:12 -0400 [thread overview]
Message-ID: <20141022001612.GB26724@oracle.com> (raw)
In-Reply-To: <5446F291.1030400@oracle.com>
On (10/21/14 18:56), Dave Kleikamp wrote:
> >
> > Is gcc not smart enough to know that this variable isn't used before
> > it's set? (I assume it isn't used elsewhere in this function)
>
> It probably assumes in_softirq() might evaluate differently in the each
> case.
yes, that's what I suspected too. I suppose it is possible
from the compiler's point of view that something in between
might change the result of in_softirq() so that we may be
using an uninit variable in the second call.
anyway, the warning was annoying, and would only numb the
user into ignoring other real issues, so I figured I might
as well silence the warning.
--Sowmini
next prev parent reply other threads:[~2014-10-22 0:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-21 14:16 [PATCHv4 3/4] sparc64: Avoid irqsave/restore on vio.lock if in_softirq() Sowmini Varadhan
2014-10-21 14:16 ` Sowmini Varadhan
2014-10-21 22:35 ` Julian Calaby
2014-10-21 22:35 ` Julian Calaby
2014-10-21 22:39 ` Sowmini Varadhan
2014-10-21 22:39 ` Sowmini Varadhan
2014-10-21 22:42 ` Julian Calaby
2014-10-21 22:42 ` Julian Calaby
2014-10-21 23:56 ` Dave Kleikamp
2014-10-21 23:56 ` Dave Kleikamp
2014-10-22 0:16 ` Sowmini Varadhan [this message]
2014-10-22 0:16 ` Sowmini Varadhan
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