From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Smith Subject: Re: [PATCH 3/4] Update the UNIX buffer restore code to match the new format saved in the image file Date: Wed, 11 Nov 2009 13:57:16 -0800 Message-ID: <87vdhgvi6b.fsf@caffeine.danplanet.com> References: <1257878856-25520-1-git-send-email-danms@us.ibm.com> <1257878856-25520-4-git-send-email-danms@us.ibm.com> <20091111213851.GE8761@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20091111213851.GE8761-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> (Serge E. Hallyn's message of "Wed\, 11 Nov 2009 15\:38\:51 -0600") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Serge E. Hallyn" Cc: containers-qjLDD68F18O7TbgM5vRIOg@public.gmane.org List-Id: containers.vger.kernel.org >> /* Make sure there's room in the send buffer */ >> sndbuf = sk->sk_sndbuf; >> - if (((sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc)) < len) && >> + if (((sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc)) < h->lin_len) && >> capable(CAP_NET_ADMIN)) >> - sk->sk_sndbuf += len; >> + sk->sk_sndbuf += h->lin_len; >> else sk-> sk_sndbuf = sysctl_wmem_max; SH> Can you explain what's going on here? If we're trying to restore a buffer that is larger than the remaining space in the buffer, then one of two things can happen: 1. You're privileged and we make the space you need 2. You're not privileged so we give you the benefit of the doubt and set the buffer limit to the system default In the case of 2, if that system default still isn't enough then the sendmsg() will fail like it normally would. The reason for this is that the application could have loaded up its legitimate buffer with data and then set the buffer limit low. That doesn't purge the data it already had buffered, it just limits how much you can add to it. So, in order to not fail a restart of such a legitimate situation, we assume the system default instead of the limit set by the user. -- Dan Smith IBM Linux Technology Center email: danms-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org