Commit:     bdcb88562ca90e6cfac13130e147c63aaa4f9e41
Parent:     3650925893469ccb03dbcc6a440c5d363350f591
Author:     Bob Peterson <[EMAIL PROTECTED]>
AuthorDate: Wed Jul 11 15:55:23 2007 -0500
Committer:  Steven Whitehouse <[EMAIL PROTECTED]>
CommitDate: Tue Aug 14 10:32:04 2007 +0100

    [GFS2] soft lockup detected in databuf_lo_before_commit
    This is part 2 of the patch for bug #245832, part 1 of which is already
    in the git tree.
    The problem was that sdp->sd_log_num_databuf was not always being
    protected by the gfs2_log_lock spinlock, but the sd_log_le_databuf
    (which it is supposed to reflect) was protected.  That meant there
    was a timing window during which gfs2_log_flush called
    databuf_lo_before_commit and the count didn't match what was
    really on the linked list in that window.  So when it ran out of
    items on the linked list, it decremented total_dbuf from 0 to -1 and
    thus never left the "while(total_dbuf)" loop.
    The solution is to protect the variable sdp->sd_log_num_databuf so
    that the value will always match the contents of the linked list,
    and therefore the number will never go negative, and therefore, the
    loop will be exited properly.
    Signed-off-by: Bob Peterson <[EMAIL PROTECTED]>
    Signed-off-by: Steven Whitehouse <[EMAIL PROTECTED]>
 fs/gfs2/lops.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index aff70f0..3b395c4 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -486,8 +486,8 @@ static void databuf_lo_add(struct gfs2_sbd *sdp, struct 
gfs2_log_element *le)
                gfs2_pin(sdp, bd->bd_bh);
-       sdp->sd_log_num_databuf++;
+       sdp->sd_log_num_databuf++;
        list_add(&le->le_list, &sdp->sd_log_le_databuf);
@@ -523,7 +523,7 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
        struct buffer_head *bh = NULL,*bh1 = NULL;
        struct gfs2_log_descriptor *ld;
        unsigned int limit;
-       unsigned int total_dbuf = sdp->sd_log_num_databuf;
+       unsigned int total_dbuf;
        unsigned int total_jdata = sdp->sd_log_num_jdata;
        unsigned int num, n;
        __be64 *ptr = NULL;
@@ -535,6 +535,7 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
         * into the log along with a header
+       total_dbuf = sdp->sd_log_num_databuf;
        bd2 = bd1 = list_prepare_entry(bd1, &sdp->sd_log_le_databuf,
        while(total_dbuf) {
@@ -653,6 +654,7 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
                bh = NULL;
+               BUG_ON(total_dbuf < num);
                total_dbuf -= num;
                total_jdata -= num;
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