Commit 341bc960 authored Feb 22, 2016 by Amir Shehata Committed by Greg Kroah-Hartman Feb 22, 2016

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>

parent 94bfb3cf

drivers/staging/lustre/lnet/lnet/module.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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);