From: Dmitry Zogin <dmitry.zoguine@oracle.com>
Date: Mon, 19 Apr 2010 23:29:32 +0000 (-0700)
Subject: b=22409 Spurious error messages from smp_processor_id() on preemptible kernel
X-Git-Tag: 1.10.0.41~36
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=58fac30e99f428438a12c6a3f4f6989ef0ec5c22;p=fs%2Flustre-release.git

b=22409 Spurious error messages from smp_processor_id() on preemptible kernel

 Disable a preemption by grabbing the lock in fs_trace_get_tcd() first.
 The function fs_trace_get_tcd() was moved up.

 o=andreas.dilger
 i=johann
 i=dmitry.zogin
 i=nathan.rutman
---

diff --git a/libcfs/libcfs/tracefile.c b/libcfs/libcfs/tracefile.c
index 5838f73..da566c0 100644
--- a/libcfs/libcfs/tracefile.c
+++ b/libcfs/libcfs/tracefile.c
@@ -261,10 +261,13 @@ int libcfs_debug_vmsg2(cfs_debug_limit_state_t *cdls, int subsys, int mask,
         if (strchr(file, '/'))
                 file = strrchr(file, '/') + 1;
 
+        tcd = cfs_trace_get_tcd();
 
+        /* cfs_trace_get_tcd() grabs a lock, which disables preemption and
+         * pins us to a particular CPU.  This avoids an smp_processor_id()
+         * warning on Linux when debugging is enabled. */
         cfs_set_ptldebug_header(&header, subsys, mask, line, CDEBUG_STACK());
 
-        tcd = cfs_trace_get_tcd();
         if (tcd == NULL)                /* arch may not log in IRQ context */
                 goto console;