1. 16 Sep, 2014 1 commit
  2. 23 Jun, 2014 1 commit
  3. 10 Jun, 2013 1 commit
    • Michael Roth's avatar
      qemu-char: don't issue CHR_EVENT_OPEN in a BH · bd5c51ee
      Michael Roth authored
      When CHR_EVENT_OPENED was initially added, it was CHR_EVENT_RESET,
      and it was issued as a bottom-half:
      
      86e94dea
      
      Which we basically used to print out a greeting/prompt for the
      monitor.
      
      AFAICT the only reason this was ever done in a BH was because in
      some cases we'd modify the chr_write handler for a new chardev
      backend *after* the site where we issued the reset (see:
      86e94d:qemu_chr_open_stdio())
      
      At some point this event was renamed to CHR_EVENT_OPENED, and we've
      maintained the use of this BH ever since.
      
      However, due to 9f939df9, we schedule
      the BH via g_idle_add(), which is causing events to sometimes be
      delivered after we've already begun processing data from backends,
      leading to:
      
       known bugs:
      
        QMP:
          session negotation resets with OPENED event, in some cases this
          is causing new sessions to get sporadically reset
      
       potential bugs:
      
        hw/usb/redirect.c:
          can_read handler checks for dev->parser != NULL, which may be
          true if CLOSED BH has not been executed yet. In the past, OPENED
          quiesced outstanding CLOSED events prior to us reading client
          data. If it's delayed, our check may allow reads to occur even
          though we haven't processed the OPENED event yet, and when we
          do finally get the OPENED event, our state may get reset.
      
        qtest.c:
          can begin session before OPENED event is processed, leading to
          a spurious reset of the system and irq_levels
      
        gdbstub.c:
          may start a gdb session prior to the machine being paused
      
      To fix these, let's just drop the BH.
      
      Since the initial reasoning for using it still applies to an extent,
      work around that by deferring the delivery of CHR_EVENT_OPENED until
      after the chardevs have been fully initialized, toward the end of
      qmp_chardev_add() (or some cases, qemu_chr_new_from_opts()). This
      defers delivery long enough that we can be assured a CharDriverState
      is fully initialized before CHR_EVENT_OPENED is sent.
      
      Also, rather than requiring each chardev to do an explicit open, do it
      automatically, and allow the small few who don't desire such behavior to
      suppress the OPENED-on-init behavior by setting a 'explicit_be_open'
      flag.
      
      We additionally add missing OPENED events for stdio backends on w32,
      which were previously not being issued, causing us to not recieve the
      banner and initial prompts for qmp/hmp.
      Reported-by: default avatarStefan Priebe <s.priebe@profihost.ag>
      Signed-off-by: default avatarMichael Roth <mdroth@linux.vnet.ibm.com>
      Message-id: 1370636393-21044-1-git-send-email-mdroth@linux.vnet.ibm.com
      Cc: qemu-stable@nongnu.org
      Signed-off-by: default avatarMichael Roth <mdroth@linux.vnet.ibm.com>
      Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
      bd5c51ee
  4. 15 Apr, 2013 1 commit
  5. 13 Mar, 2013 1 commit
  6. 01 Mar, 2013 1 commit
  7. 19 Dec, 2012 2 commits
  8. 24 Feb, 2012 1 commit
    • Markus Armbruster's avatar
      Revert "qemu-char: Print strerror message on failure" and deps · 1f51470d
      Markus Armbruster authored
      The commit's purpose is laudable:
      
          The only way for chardev drivers to communicate an error was to
          return a NULL pointer, which resulted in an error message that
          said _that_ something went wrong, but not _why_.
      
      It attempts to achieve it by changing the interface to return 0/-errno
      and update qemu_chr_open_opts() to use strerror() to display a more
      helpful error message.  Unfortunately, it has serious flaws:
      
      1. Backends "socket" and "udp" return bogus error codes, because
      qemu_chr_open_socket() and qemu_chr_open_udp() assume that
      unix_listen_opts(), unix_connect_opts(), inet_listen_opts(),
      inet_connect_opts() and inet_dgram_opts() fail with errno set
      appropriately.  That assumption is wrong, and the commit turns
      unspecific error messages into misleading error messages.  For
      instance:
      
          $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx
          inet_connect: host and/or port not specified
          chardev: opening backend "socket" failed: No such file or directory
      
      ENOENT is what happens to be in my errno when the backend returns
      -errno.  Let's put ERANGE there just for giggles:
      
          $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx -drive if=none,iops=99999999999999999999
          inet_connect: host and/or port not specified
          chardev: opening backend "socket" failed: Numerical result out of range
      
      Worse: when errno happens to be zero, return -errno erroneously
      signals success, and qemu_chr_new_from_opts() dies dereferencing
      uninitialized chr.  I observe this with "-serial unix:".
      
      2. All qemu_chr_open_opts() knows about the error is an errno error
      code.  That's simply not enough for a decent message.  For instance,
      when inet_dgram() can't resolve the parameter host, which errno code
      should it use?  What if it can't resolve parameter localaddr?
      
      Clue: many backends already report errors in their open methods.
      Let's revert the flawed commit along with its dependencies, and fix up
      the silent error paths instead.
      
      This reverts commit 6e1db57b.
      
      Conflicts:
      
      	console.c
      	hw/baum.c
      	qemu-char.c
      
      This reverts commit aad04cd0.
      
      The parts of commit db418a0a "Add stdio char device on windows" that
      depend on the reverted change fixed up.
      Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
      Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
      1f51470d
  9. 22 Aug, 2011 1 commit
  10. 20 Aug, 2011 1 commit
  11. 23 Jul, 2011 1 commit
  12. 11 Sep, 2009 1 commit
  13. 08 Feb, 2009 1 commit