libxl: make GC_FREE reachable in libxl_get_scheduler()

Coverity CID 1343309

Make GC_FREE reachable in all cases in libxl_get_scheduler() by
eliminating the error-path return and instead storing the error code in
the returned variable.

To make this semantically consistent, change the return type of
libxl_get_scheduler() from libxl_scheduler to int, and make a note of
the interpretation of the return value in libxl.h.  N.B. This change
does not change the API in a way that affects functionality.

The libxl_scheduler enum is consistent with the sched_id return value
of xc_sched_id and this must continue to be true.

Suggested-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Chester Lin <czylin@uwaterloo.ca>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 52fefc0590e3e1ca6a173ab5234ab0b6b5566975..94b565604f014cc5f891871e71f33545e62bcd49 100644 (file)
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5578,7 +5578,7 @@ out:
     return rc;
 }
 
-libxl_scheduler libxl_get_scheduler(libxl_ctx *ctx)
+int libxl_get_scheduler(libxl_ctx *ctx)
 {
     int r, sched;
 
@@ -5586,8 +5586,7 @@ libxl_scheduler libxl_get_scheduler(libxl_ctx *ctx)
     r = xc_sched_id(ctx->xch, &sched);
     if (r != 0) {
         LOGE(ERROR, "getting current scheduler id");
-        return ERROR_FAIL;
-        GC_FREE;
+        sched = ERROR_FAIL;
     }
     GC_FREE;
     return sched;

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 156c0d50f8556b758372ce01df5f94aea2f9a70e..fa87f5317a4e68244c260fcec3a41ebd5bff5cae 100644 (file)
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1716,7 +1716,10 @@ int libxl_domain_get_nodeaffinity(libxl_ctx *ctx, uint32_t domid,
                                   libxl_bitmap *nodemap);
 int libxl_set_vcpuonline(libxl_ctx *ctx, uint32_t domid, libxl_bitmap *cpumap);
 
-libxl_scheduler libxl_get_scheduler(libxl_ctx *ctx);
+/* A return value less than 0 should be interpreted as a libxl_error, while a
+ * return value greater than or equal to 0 should be interpreted as a
+ * libxl_scheduler. */
+int libxl_get_scheduler(libxl_ctx *ctx);
 
 /* Per-scheduler parameters */
 int libxl_sched_credit_params_get(libxl_ctx *ctx, uint32_t poolid,