[SCSI] sg: fix leak when dio setup fails

when the sg driver is unable to setup direct IO, free that scatter
gather list prior to falling back to indirect IO

Further to this thread started by Bryan Holty:
http://marc.theaimsgroup.com/?l=linux-scsi&m=114306885116728&w=2

Here is the reworked patch again. This time it has been
tested with a program provided by Bryan.

Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index bfa86b378fb9659c18d25a399593f9f431dc0600..b098942445ec0c43a31b041d1d25e943d28ad55e 100644 (file)
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1799,8 +1799,10 @@ sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len)
        res = st_map_user_pages(schp->buffer, mx_sc_elems,
                                (unsigned long)hp->dxferp, dxfer_len, 
                                (SG_DXFER_TO_DEV == hp->dxfer_direction) ? 1 : 0);
-       if (res <= 0)
+       if (res <= 0) {
+               sg_remove_scat(schp);
                return 1;
+       }
        schp->k_use_sg = res;
        schp->dio_in_use = 1;
        hp->info |= SG_INFO_DIRECT_IO;