[Xen-devel] [PATCH v3 2/5] libxl: make GC_FREE reachable in libxl_get_scheduler()

[Chester Lin <czylin@xxxxxxxxxxxx>]

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@xxxxxxxxxx>
Signed-off-by: Chester Lin <czylin@xxxxxxxxxxxx>
Reviewed-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>

---
Changed return type of libxl_get_scheduler in order to return both negative
error constants and positive scheduler values.
---
 tools/libxl/libxl.c | 5 ++---
 tools/libxl/libxl.h | 5 ++++-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 9c3cb3e..5a450ef 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5582,7 +5582,7 @@ out:
     return rc;
 }
 
-libxl_scheduler libxl_get_scheduler(libxl_ctx *ctx)
+int libxl_get_scheduler(libxl_ctx *ctx)
 {
     int r, sched;
 
@@ -5590,8 +5590,7 @@ 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 7114491..09fcef3 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1711,7 +1711,10 @@ 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,
-- 
1.9.5.msysgit.0


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