OpenAFS Master Repository branch, openafs-stable-1_8_x, updated. openafs-stable-1_8_5-12-g9f38cbd

[Gerrit Code Review]

The following commit has been merged in the openafs-stable-1_8_x branch:
commit 9f38cbdc544d6659c60dbd578e86110df86457b6
Author: Mark Vitale <mvitale@sinenomine.net>
Date:   Tue Sep 17 15:14:44 2019 -0400

    viced: consistently enforce host thread quota for ICBS(3)
    
    From time to time, the fileserver may issue potentially long-running
    RXAFSCB_* RPCs back to a host (client).  If these are holding h_Lock_r
    (host->lock) while running, they may cause other service threads for the
    same host (client) to block.
    
    In order to prevent a given host from tying up too many service threads
    in this way, the fileserver enforces a quota limiting how many threads
    can be waiting for h_Lock_r on a particular host while waiting for one
    of the following RPCs to complete:
    - RXAFSCB_TellMeABoutYourself (TMAY)
    - RXAFSCB_WhoAreYou
    - RXAFSCB_ProbeUuid
    - RXAFSCB_InitCallBackState (ICBS)
    - RXAFSCB_InitCallBackState3 (ICBS3)
    
    Note: Although some of these RPCs are relatively lightweight, they may
    still experience network delays.
    
    This quota is enforced by calling h_threadquota() in h_Lookup_r and
    h_GetHost_r.  The quota check is enabled for a given host by turning on
    host->hostFlags HWHO_INPROGRESS for the duration of the RXAFSCB_* RPC.
    The quota check is only needed, and should only be enabled, when the RPC
    is issued while h_Lock_r is held.
    
    However, there are a few paths to ICBS(3) where h_Lock_r is held but
    HWHO_INPROGRESS is not set.  A delay in those paths may allow a host to
    consume an unlimited number of fileserver threads.  One such path
    observed in a field report was SRXAFS_FetchStatus -> CallPreamble ->
    BreakDelayedCallBacks_r -> RXAFSCB_ICBS3.
    
    Instead, enable host thread quotas for all remaining unregulated ICBS(3)
    RPCs.
    
    Reviewed-on: https://gerrit.openafs.org/13873
    Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    (cherry picked from commit aefc4c4f46e13f59b4cbe043e1a2a6f4ed99e076)
    
    Change-Id: If3883a152078bba9995e0c8a13ab31788db6347f
    Reviewed-on: https://gerrit.openafs.org/13893
    Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
    Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
    Reviewed-by: Andrew Deason <adeason@sinenomine.net>
    Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
    Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>

 src/viced/callback.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

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