From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel P. Berrange" Subject: PATCH: improve robustness of xenconsoled logfile handling Date: Tue, 26 Jun 2007 20:48:58 +0100 Message-ID: <20070626194858.GE6220@redhat.com> Reply-To: "Daniel P. Berrange" Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="/04w6evG8XlLl3ft" Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org --/04w6evG8XlLl3ft Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Attached is an small patch to xenconsoled to make the persistent logging code I previously added a little more robust. First change is to check the 'log_reload' on every iteration of the select() loop, not just when select() returns EINTR. This is because the log reload signal may have iterrupted a syscall other than select & thus without this change we might miss the reload signal. The second change makes us process the hypervisor logs on every iteration of the loop, not just upon timeouts. This is because if a guest VM were consistently sending some log message and < 1 second period, the select() would never hit the 1 second timeout and thus never process the HV logs. Thanks to Markus Armbruster for pointing out both these edge cases Signed-off-by: Daniel P. Berrange io.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=| --/04w6evG8XlLl3ft Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="xen-console-log-paranoia.patch" diff -r 9261686d840c tools/console/daemon/io.c --- a/tools/console/daemon/io.c Tue Jun 26 12:40:37 2007 +0100 +++ b/tools/console/daemon/io.c Tue Jun 26 15:36:36 2007 -0400 @@ -766,23 +766,27 @@ void handle_io(void) * for new HV log data as we can with guest */ ret = select(max_fd + 1, &readfds, &writefds, 0, log_hv_fd != -1 ? &timeout : NULL); + if (log_reload) { + handle_log_reload(); + log_reload = 0; + } + + /* Abort if select failed, except for EINTR cases + which indicate a possible log reload */ if (ret == -1) { - if (errno == EINTR) { - if (log_reload) { - handle_log_reload(); - log_reload = 0; - } + if (errno == EINTR) continue; - } dolog(LOG_ERR, "Failure in select: %d (%s)", errno, strerror(errno)); break; } - /* Check for timeout */ + /* Always process HV logs even if not a timeout */ + if (log_hv_fd != -1) + handle_hv_logs(); + + /* Must not check returned FDSET if it was a timeout */ if (ret == 0) { - if (log_hv_fd != -1) - handle_hv_logs(); continue; } @@ -806,10 +810,14 @@ void handle_io(void) } } - if (log_hv_fd != -1) + if (log_hv_fd != -1) { close(log_hv_fd); - if (xc_handle != -1) + log_hv_fd = -1; + } + if (xc_handle != -1) { xc_interface_close(xc_handle); + xc_handle = -1; + } } /* --/04w6evG8XlLl3ft Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --/04w6evG8XlLl3ft--