LU-15689 libcfs: libcfs_debug_mb set incorrectly on init

If libcfs_debug_mb parameter is specified to insmod (i.e. set before
module is initialized) then it does not get initialized correctly.

libcfs_param_debug_mb_set() expects cfs_trace_get_debug_mb() to return
zero if the module has not been initialized yet, but
cfs_trace_get_debug_mb() will return 1 in this case. Modify
cfs_trace_get_debug_mb() to return zero as expected. A related issue
is that in this case we need to call cfs_trace_get_debug_mb() after
cfs_tracefile_init() so that libcfs_debug_mb gets the same value it
would get if we had set it after module init.

When libcfs_debug_mb is specified to insmod, libcfs_debug_init()
divides its value by num_possible_cpus(), but this is already done in
libcfs_param_debug_mb_set().

Test-Parameters: trivial
Fixes: 8b78a3ffb5 ("LU-9859 libcfs: always range-check libcfs_debug_mb setting.")
HPE-bug-id: LUS-10839
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: I1003758156acb5cf6ea30bbdfd7b45a743a2a5aa
Reviewed-on: https://review.whamcloud.com/46925
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/libcfs/libcfs/debug.c b/libcfs/libcfs/debug.c
index f8ad146..a0dbffa 100644 (file)
--- a/libcfs/libcfs/debug.c
+++ b/libcfs/libcfs/debug.c
@@ -684,12 +684,10 @@ int libcfs_debug_init(unsigned long bufsize)
        /* If libcfs_debug_mb is uninitialized then just make the
         * total buffers smp_num_cpus * TCD_MAX_PAGES
         */
-       if (max < num_possible_cpus()) {
+       if (max < num_possible_cpus())
                max = TCD_MAX_PAGES;
-       } else {
-               max = (max / num_possible_cpus());
+       else
                max <<= (20 - PAGE_SHIFT);
-       }
 
        rc = cfs_tracefile_init(max);
        if (rc)
@@ -697,8 +695,7 @@ int libcfs_debug_init(unsigned long bufsize)
 
        libcfs_register_panic_notifier();
        kernel_param_lock(THIS_MODULE);
-       if (libcfs_debug_mb == 0)
-               libcfs_debug_mb = cfs_trace_get_debug_mb();
+       libcfs_debug_mb = cfs_trace_get_debug_mb();
        kernel_param_unlock(THIS_MODULE);
        return rc;
 }

diff --git a/libcfs/libcfs/tracefile.c b/libcfs/libcfs/tracefile.c
index ac473c5..d79ec06 100644 (file)
--- a/libcfs/libcfs/tracefile.c
+++ b/libcfs/libcfs/tracefile.c
@@ -967,7 +967,10 @@ int cfs_trace_get_debug_mb(void)
 
        up_read(&cfs_tracefile_sem);
 
-       return (total_pages >> (20 - PAGE_SHIFT)) + 1;
+       if (total_pages)
+               return (total_pages >> (20 - PAGE_SHIFT)) + 1;
+       else
+               return 0;
 }
 
 static int tracefiled(void *arg)