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staging: lustre: prevent assert on LNet module unload 

There is a use case where lnet can be unloaded while there are
no NIs configured.  Removing lnet in this case will cause
LNetFini() to be called without a prior call to LNetNIFini().
This will cause the LASSERT(the_lnet.ln_refcount == 0) to be
triggered.

To deal with this use case when LNet is configured a reference
count on the module is taken using try_module_get().  This way
LNet must be unconfigured before it could be removed; therefore
avoiding the above case.  When LNet is unconfigured module_put()
is called to return the reference count.

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6010
Reviewed-on: http://review.whamcloud.com/13110
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Amir Shehata 2016-02-22 17:29:18 -05:00 committed by Greg Kroah-Hartman
parent 94bfb3cff2
commit 341bc96085
1 changed files with 9 additions and 0 deletions
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9
drivers/staging/lustre/lnet/lnet/module.c
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@ -53,13 +53,21 @@ lnet_configure(void *arg)
mutex_lock(&lnet_config_mutex);
if (!the_lnet.ln_niinit_self) {
rc = try_module_get(THIS_MODULE);
if (rc != 1)
goto out;
rc = LNetNIInit(LNET_PID_LUSTRE);
if (rc >= 0) {
the_lnet.ln_niinit_self = 1;
rc = 0;
} else {
module_put(THIS_MODULE);
}
}
out:
mutex_unlock(&lnet_config_mutex);
return rc;
}
@ -74,6 +82,7 @@ lnet_unconfigure(void)
if (the_lnet.ln_niinit_self) {
the_lnet.ln_niinit_self = 0;
LNetNIFini();
module_put(THIS_MODULE);
}
mutex_lock(&the_lnet.ln_api_mutex);