[Xen-devel] [PATCH] libxl: Add a gc to libxl_cpumap_alloc, ..._to_hex_string

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

This need to be slotted into my save/restore series, since a new case
of libxl__*alloc(0,...) was just added.

Thanks,
Ian.

From: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Subject: [PATCH] libxl: Add a gc to libxl_cpumap_alloc, ..._to_hex_string

In the next patch we are going to change the definition of NOGC to
require a local variable libxl__gc *gc.  And this means that passing 0
to libxl__calloc is going to be wrong.

libxl_cpumap_alloc doesn't have a gc but passes 0 to libxl_calloc
Fix this by:
 - introducing an `out' label and an rc variable
 - replacing the returns with  rc = ERROR_BLAH; goto out;
 - adding uses of GC_INIT and GC_FREE.
 - changing NULL to NOGC in the call to libxl__calloc

Likewise fix libxl_cpumap_to_hex_string by:
 - adding a libxl_ctx* parameter and updating the one call site
 - adding uses of GC_INIT and GC_FREE.
 - changing NULL to NOGC in the call to libxl__zalloc

Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

---
 tools/libxl/libxl_dm.c    |    2 +-
 tools/libxl/libxl_utils.c |   28 ++++++++++++++++++++--------
 tools/libxl/libxl_utils.h |    2 +-
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 2edc734..936e307 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -204,7 +204,7 @@ static char ** libxl__build_device_model_args_old(libxl__gc 
*gc,
         }
 
         nr_set_cpus = libxl_cpumap_count_set(&b_info->avail_vcpus);
-        s = libxl_cpumap_to_hex_string(&b_info->avail_vcpus);
+        s = libxl_cpumap_to_hex_string(CTX, &b_info->avail_vcpus);
         flexarray_vappend(dm_args, "-vcpu_avail",
                               libxl__sprintf(gc, "%s", s), NULL);
         free(s);
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index d07a5a7..7073062 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -491,19 +491,29 @@ int libxl_mac_to_device_nic(libxl_ctx *ctx, uint32_t 
domid,
 
 int libxl_cpumap_alloc(libxl_ctx *ctx, libxl_cpumap *cpumap, int max_cpus)
 {
+    GC_INIT(ctx);
     int sz;
+    int rc;
 
-    if (max_cpus < 0)
-        return ERROR_INVAL;
+    if (max_cpus < 0) {
+        rc = ERROR_INVAL;
+        goto out;
+    }
     if (max_cpus == 0)
         max_cpus = libxl_get_max_cpus(ctx);
-    if (max_cpus == 0)
-        return ERROR_FAIL;
+    if (max_cpus == 0) {
+        rc = ERROR_FAIL;
+        goto out;
+    }
 
     sz = (max_cpus + 7) / 8;
-    cpumap->map = libxl__calloc(NULL, sizeof(*cpumap->map), sz);
+    cpumap->map = libxl__calloc(NOGC, sizeof(*cpumap->map), sz);
     cpumap->size = sz;
-    return 0;
+
+    rc = 0;
+ out:
+    GC_FREE;
+    return rc;
 }
 
 void libxl_cpumap_dispose(libxl_cpumap *map)
@@ -542,10 +552,11 @@ int libxl_cpumap_count_set(const libxl_cpumap *cpumap)
 }
 
 /* NB. caller is responsible for freeing the memory */
-char *libxl_cpumap_to_hex_string(const libxl_cpumap *cpumap)
+char *libxl_cpumap_to_hex_string(libxl_ctx *ctx, const libxl_cpumap *cpumap)
 {
+    GC_INIT(ctx);
     int i = cpumap->size;
-    char *p = libxl__zalloc(NULL, cpumap->size * 2 + 3);
+    char *p = libxl__zalloc(NOGC, cpumap->size * 2 + 3);
     char *q = p;
     strncpy(p, "0x", 2);
     p += 2;
@@ -554,6 +565,7 @@ char *libxl_cpumap_to_hex_string(const libxl_cpumap *cpumap)
         p += 2;
     }
     *p = '\0';
+    GC_FREE;
     return q;
 }
 
diff --git a/tools/libxl/libxl_utils.h b/tools/libxl/libxl_utils.h
index a762734..05a269a 100644
--- a/tools/libxl/libxl_utils.h
+++ b/tools/libxl/libxl_utils.h
@@ -68,7 +68,7 @@ int libxl_cpumap_test(const libxl_cpumap *cpumap, int cpu);
 void libxl_cpumap_set(libxl_cpumap *cpumap, int cpu);
 void libxl_cpumap_reset(libxl_cpumap *cpumap, int cpu);
 int libxl_cpumap_count_set(const libxl_cpumap *cpumap);
-char *libxl_cpumap_to_hex_string(const libxl_cpumap *cpumap);
+char *libxl_cpumap_to_hex_string(libxl_ctx *ctx, const libxl_cpumap *cpumap);
 static inline void libxl_cpumap_set_any(libxl_cpumap *cpumap)
 {
     memset(cpumap->map, -1, cpumap->size);
-- 
tg: (197c736..) t/xen/xl.nogc.add-gcs.cpumap (depends on: t/xen/xl.nogc.add-gcs)

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