[SCM] systemtap: system-wide probe/trace tool branch, mjw/release-1.4-transport, created. release-1.4-4-g3a00926

[mark at sourceware dot org]

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The branch, mjw/release-1.4-transport has been created
        at  3a009261e70994c76b42a67285ff08f86542528e (commit)

- Log -----------------------------------------------------------------
commit 3a009261e70994c76b42a67285ff08f86542528e
Author: Mark Wielaard <mjw@redhat.com>
Date:   Mon Jul 18 20:55:38 2011 +0200

    PR10189 and PR12960 reserve system cmd messages for delivery.
    
    runtime/transport/control.c kept one pool for all cmd messages that
    the module had to deliver to staprun/io.  This pool could become
    empty.  This meant essential control message would not be delivered.
    Leading to the module not properly starting and/or exiting.
    
    We now set aside buffers for one time messages (STP_START, STP_EXIT,
    STP_TRANSPORT, STAP_REQUEST_EXIT) and "overflow" messages that get
    delivered whenever one of the dynamically allocated messages cannot
    get a free slot from the pool (STP_OOB_DATA - warnings and errors,
    STP_SYSTEM and STP_REALTIME_DATA).
    
    The type field is used to mark whether or not a special pre-allocated
    buffer is currently unused. This needs careful locking using a new
    &_stp_ctl_special_msg_lock that is used in the new helper functions
    _stp_ctl_get_buffer and _stp_ctl_free_buffer.
    
    Now when we run out of message buffers we just drop the message and
    printk. stapio will have received either the one time message or an
    overflow message, there is nothing more we can do.
    
    The STP_DEFAULT_BUFFERS for debugfs.c got decreased again to allow
    8 pre-allocated and 32 dynamic (pending) cmd messages.
    
    A new testcase testsuite/systemtap.base/warn_overflow.exp was added.

commit f7ed4bb6de5a27cfb50e6447e98b890acf3f931c
Author: Mark Wielaard <mjw@redhat.com>
Date:   Fri Jul 15 23:54:47 2011 +0200

    PR12960 Don't msleep in _stp_ctl_send when out of memory.
    
    This is mainly a documentation patch to better explain the transport
    layers and the interaction between _stp_ctl_read_cmd, _stp_ctl_send and
    _stp_ctl_write.
    
    It also contains the first step to resolve PR12960. The msleep() in
    _stp_ctl_send() has been replaced with a loop that checks whether there
    are messages on the queue, tries to wake up _stp_ctl_read_cmd so stapio
    has a change to read some of the pending messages and a small mdelay
    (which is save, because it doesn't actually sleep or schedule). It
    only prevents the crash and makes the possibility of loosing control
    messages slightly less. A followup patch will introduce special buffers
    to hold cannot be lost messages so the module will always be able to
    properly shut down.
    
    STP_DEFAULT_BUFFERS for debugfs also got increased a little from 50 to 64.

commit 37b9c1f7c89d499333068ab73292dfcad2e70c15
Author: Mark Wielaard <mjw@redhat.com>
Date:   Fri Jul 15 17:06:52 2011 +0200

    Create dropped file with mode 0400 in relay_v2.c to make it not world readable.

commit 2696e0cb7566ed999c8bfe1cc9d22ebd7962243e
Author: Mark Wielaard <mjw@redhat.com>
Date:   Fri Jul 15 15:11:41 2011 +0200

    Document stp control channel command values under runtime/transport.

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