linux-kernel - Re: Suspected sock_sendmsg() with MSG

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Message-ID: <878wnv4yq1.fsf@basil.nowhere.org>
Date:	Tue, 24 Feb 2009 16:54:30 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Parav Pandit <paravpandit@...oo.com>
Cc:	Linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: Suspected sock_sendmsg() with MSG_DONTWAIT can block bug.

Parav Pandit <paravpandit@...oo.com> writes:

> Short quick question:
> ---------------------
> If sock_sendmsg() is calls with MSG_DONTWAIT, it should send the packet without blocking the context or fail the call with error value.

It is allowed to fail with errors.

> Which means sock_sendmsg() with MSG_DONTWAIT can be called from soft-irq/ interrupt ctx.
> Is that correct?

No. It can still block for memory for example. Also there's no irq locking
in place Irq context is not allowed. MSG_DONTWAIT just means don't block
on buffer space or connection finish.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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