[haiku-bugs] [Haiku] #9798: mount_nfs hangs, blocked in nfs add on
- From: "jua" <trac@xxxxxxxxxxxx>
- Date: Sun, 26 May 2013 22:18:05 -0000
#9798: mount_nfs hangs, blocked in nfs add on
--------------------------------+------------------------------
Reporter: jua | Owner: nobody
Type: bug | Status: new
Priority: normal | Milestone: R1
Component: Network & Internet | Version: R1/Development
Keywords: nfs nfs_mount | Blocked By:
Blocking: | Has a Patch: 0
Platform: All |
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hrev45633
While trying to mount NFS shares (old NFS, not v4) using mount_nfs,
something goes wrong and the command line tool simply hangs and is then
unkillable. It can neither be killed with Ctrl+C in the terminal, nor via
ProcessController. The only way to get rid of it is a reboot.
I've tracked the problem down to the NFS file system add-on, the following
happens in there:
(1) fs_mount() in nfs_add_on.c calls nfs_mount(), which fails for some
reason (why that fails is possibly material for another bug report, have
not investigated that yet)
(2) fs_mount() thus goes to its error handling and calls
shutdown_postoffice()
(3) shutdown_postoffice() sets the quit-flag for the postoffice-thread to
true, closes the socket and then waits for the postoffice-thread to exit
using wait_for_thread(). This wait_for_thread() never returns and causes
the hanging.
(4) ... meanwhile in the postoffice-thread: The postoffice-thread is
currently in recvfrom() inside its main loop in postoffice_func(). Since
nothing is received anymore, it waits there forever and doesn't see that
its quit flag was set, so it never terminates.
(5) => deadlock!
I'm not quite sure what the correct way to handle it would be -- maybe a
simple workaround would be to set a read timeout on the socket so the
postoffice thread would terminate at least at some point. Any ideas?
--
Ticket URL: <http://dev.haiku-os.org/ticket/9798>
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