atl1: fix oops when changing tx/rx ring params [Linux 2.6.37]

This Linux kernel change "atl1: fix oops when changing tx/rx ring params" is included in the Linux 2.6.37 release. This change is authored by J. K. Cliburn <jcliburn [at] gmail.com> on Sat Jan 1 05:02:12 2011 +0000. The commit for this change in Linux stable tree is 2f32c86 (patch).

atl1: fix oops when changing tx/rx ring params

Commit 3f5a2a713aad28480d86b0add00c68484b54febc zeroes out the statistics
message block (SMB) and coalescing message block (CMB) when adapter ring
resources are freed.  This is desirable behavior, but, as a side effect,
the commit leads to an oops when atl1_set_ringparam() attempts to alter
the number of rx or tx elements in the ring buffer (by using ethtool
-G, for example).  We don't want SMB or CMB to change during this
operation.

Modify atl1_set_ringparam() to preserve SMB and CMB when changing ring
parameters.

Cc: [email protected]
Signed-off-by: Jay Cliburn <[email protected]>
Reported-by: T├Ánu Raitviir <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

There are 10 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/net/atlx/atl1.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/atlx/atl1.c b/drivers/net/atlx/atl1.c
index 5336310..3acf512 100644
--- a/drivers/net/atlx/atl1.c
+++ b/drivers/net/atlx/atl1.c
@@ -3504,6 +3504,8 @@ static int atl1_set_ringparam(struct net_device *netdev,
    struct atl1_rfd_ring rfd_old, rfd_new;
    struct atl1_rrd_ring rrd_old, rrd_new;
    struct atl1_ring_header rhdr_old, rhdr_new;
+   struct atl1_smb smb;
+   struct atl1_cmb cmb;
    int err;

    tpd_old = adapter->tpd_ring;
@@ -3544,11 +3546,19 @@ static int atl1_set_ringparam(struct net_device *netdev,
        adapter->rrd_ring = rrd_old;
        adapter->tpd_ring = tpd_old;
        adapter->ring_header = rhdr_old;
+       /*
+        * Save SMB and CMB, since atl1_free_ring_resources
+        * will clear them.
+        */
+       smb = adapter->smb;
+       cmb = adapter->cmb;
        atl1_free_ring_resources(adapter);
        adapter->rfd_ring = rfd_new;
        adapter->rrd_ring = rrd_new;
        adapter->tpd_ring = tpd_new;
        adapter->ring_header = rhdr_new;
+       adapter->smb = smb;
+       adapter->cmb = cmb;

        err = atl1_up(adapter);
        if (err)

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