[Xen-devel] [PATCH v2][linux 2.6.18] scsiback: free resources after error

["Jan Beulich" <JBeulich@xxxxxxxx>]

From: Juergen Gross <jgross@xxxxxxxx>

In case of an error during preparing an I/O the already allocated resources
should all be freed again and the frontend request should be terminated
accordingly.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Some formatting adjustments to the changes above, and some more releasing
of resources (in the VSCSIIF_ACT_SCSI_RESET and default cases of the switch
in scsiback_do_cmd_fn()).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/drivers/xen/scsiback/common.h
+++ b/drivers/xen/scsiback/common.h
@@ -163,13 +163,13 @@ struct scsi_device *scsiback_do_translat
 void scsiback_release_translation_entry(struct vscsibk_info *info);
 
 
-void scsiback_cmd_exec(pending_req_t *pending_req);
+int scsiback_cmd_exec(pending_req_t *pending_req);
 void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
                        uint32_t resid, pending_req_t *pending_req);
 void scsiback_fast_flush_area(pending_req_t *req);
 
 void scsiback_rsp_emulation(pending_req_t *pending_req);
-void scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req);
+int scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req);
 void scsiback_emulation_init(void);
 
 
--- a/drivers/xen/scsiback/emulate.c
+++ b/drivers/xen/scsiback/emulate.c
@@ -345,16 +345,16 @@ void scsiback_rsp_emulation(pending_req_
 }
 
 
-void scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req)
+int scsiback_req_emulation_or_cmdexec(pending_req_t *pending_req)
 {
-       if (__pre_do_emulation(pending_req, NULL)) {
-               scsiback_cmd_exec(pending_req);
-       }
-       else {
-               scsiback_fast_flush_area(pending_req);
-               scsiback_do_resp_with_sense(pending_req->sense_buffer,
-                 pending_req->rslt, pending_req->resid, pending_req);
-       }
+       if (__pre_do_emulation(pending_req, NULL))
+               return scsiback_cmd_exec(pending_req);
+
+       scsiback_fast_flush_area(pending_req);
+       scsiback_do_resp_with_sense(pending_req->sense_buffer,
+                                   pending_req->rslt, pending_req->resid,
+                                   pending_req);
+       return 0;
 }
 
 
--- a/drivers/xen/scsiback/scsiback.c
+++ b/drivers/xen/scsiback/scsiback.c
@@ -429,14 +429,14 @@ free_bios:
 }
 
 
-void scsiback_cmd_exec(pending_req_t *pending_req)
+int scsiback_cmd_exec(pending_req_t *pending_req)
 {
        int cmd_len  = (int)pending_req->cmd_len;
        int data_dir = (int)pending_req->sc_data_direction;
        unsigned int nr_segments = (unsigned int)pending_req->nr_segments;
        unsigned int timeout;
        struct request *rq;
-       int write;
+       int write, err;
 
        DPRINTK("%s\n",__FUNCTION__);
 
@@ -463,17 +463,19 @@ void scsiback_cmd_exec(pending_req_t *pe
        rq->end_io_data = pending_req;
 
        if (nr_segments) {
-
-               if (request_map_sg(rq, pending_req, nr_segments)) {
-                       printk(KERN_ERR "scsiback: SG Request Map Error\n");
-                       return;
+               err = request_map_sg(rq, pending_req, nr_segments);
+               if (err) {
+                       printk(KERN_ERR "scsiback: SG Request Map error %d\n",
+                              err);
+                       blk_put_request(rq);
+                       return err;
                }
        }
 
        scsiback_get(pending_req->info);
        blk_execute_rq_nowait(rq->q, NULL, rq, 1, scsiback_cmd_done);
 
-       return ;
+       return 0;
 }
 
 
@@ -615,17 +617,28 @@ static int scsiback_do_cmd_fn(struct vsc
                switch (err ?: pending_req->act) {
                case VSCSIIF_ACT_SCSI_CDB:
                        /* The Host mode is through as for Emulation. */
-                       if (info->feature == VSCSI_TYPE_HOST)
-                               scsiback_cmd_exec(pending_req);
-                       else
-                               scsiback_req_emulation_or_cmdexec(pending_req);
+                       if (info->feature == VSCSI_TYPE_HOST ?
+                           scsiback_cmd_exec(pending_req) :
+                           scsiback_req_emulation_or_cmdexec(pending_req)) {
+                               scsiback_fast_flush_area(pending_req);
+                               scsiback_do_resp_with_sense(NULL,
+                                                           DRIVER_ERROR << 24,
+                                                           0, pending_req);
+                       }
                        break;
                case VSCSIIF_ACT_SCSI_RESET:
+                       /* Just for pointlessly specified segments: */
+                       scsiback_fast_flush_area(pending_req);
                        scsiback_device_reset_exec(pending_req);
                        break;
                default:
-                       if(!err && printk_ratelimit())
-                               printk(KERN_ERR "scsiback: invalid request\n");
+                       if(!err) {
+                               scsiback_fast_flush_area(pending_req);
+                               if (printk_ratelimit())
+                                       printk(KERN_ERR
+                                              "scsiback: invalid request 
%#x\n",
+                                              pending_req->act);
+                       }
                        scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24,
                                                    0, pending_req);
                        break;

Attachment: xen-scsiback-free-resources-after-error.patch
Description: Text document

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