[Xen-devel] [PATCH 16/31] libxl: abolish libxl_ctx_postfork

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

libxl's task has become too complicated (particularly in the presence
of both forking and multithreading) to support reuse of the same
libxl_ctx after fork.

So abolish libxl_ctx_fork.  xl instead simply initialises a new
libxl_ctx.

Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 tools/libxl/libxl.h       |    1 -
 tools/libxl/libxl_utils.c |    7 -------
 tools/libxl/xl.c          |    8 ++++++++
 tools/libxl/xl.h          |    1 +
 tools/libxl/xl_cmdimpl.c  |    8 ++------
 5 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index b376316..edbca53 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -461,7 +461,6 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
                     unsigned flags /* none currently defined */,
                     xentoollog_logger *lg);
 int libxl_ctx_free(libxl_ctx *ctx /* 0 is OK */);
-int libxl_ctx_postfork(libxl_ctx *ctx);
 
 /* domain related functions */
 typedef int (*libxl_console_ready)(libxl_ctx *ctx, uint32_t domid, void *priv);
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index d6cd78d..0cbd85e 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -365,13 +365,6 @@ READ_WRITE_EXACTLY(read, 1, /* */)
 READ_WRITE_EXACTLY(write, 0, const)
 
 
-int libxl_ctx_postfork(libxl_ctx *ctx) {
-    if (ctx->xsh) xs_daemon_destroy_postfork(ctx->xsh);
-    ctx->xsh = xs_daemon_open();
-    if (!ctx->xsh) return ERROR_FAIL;
-    return 0;
-}
-
 pid_t libxl_fork(libxl_ctx *ctx)
 {
     pid_t pid;
diff --git a/tools/libxl/xl.c b/tools/libxl/xl.c
index 2b14814..62c0abd 100644
--- a/tools/libxl/xl.c
+++ b/tools/libxl/xl.c
@@ -94,6 +94,14 @@ static void parse_global_config(const char *configfile,
     xlu_cfg_destroy(config);
 }
 
+void postfork(void)
+{
+    if (libxl_ctx_alloc(&ctx, LIBXL_VERSION, 0, (xentoollog_logger*)logger)) {
+        fprintf(stderr, "cannot reinit xl context after fork\n");
+        exit(-1);
+    }
+}
+
 int main(int argc, char **argv)
 {
     int opt = 0;
diff --git a/tools/libxl/xl.h b/tools/libxl/xl.h
index 0a3d628..7e258d5 100644
--- a/tools/libxl/xl.h
+++ b/tools/libxl/xl.h
@@ -105,6 +105,7 @@ struct cmd_spec *cmdtable_lookup(const char *s);
 
 extern libxl_ctx *ctx;
 extern xentoollog_logger_stdiostream *logger;
+void postfork(void);
 
 /* global options */
 extern int autoballoon;
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 6f4dd09..c9e9943 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1441,7 +1441,7 @@ static int autoconnect_console(libxl_ctx *ctx, uint32_t 
domid, void *priv)
     } else if (*pid > 0)
         return 0;
 
-    libxl_ctx_postfork(ctx);
+    postfork();
 
     sleep(1);
     libxl_primary_console_exec(ctx, domid);
@@ -1728,11 +1728,7 @@ start:
             goto out;
         }
 
-        rc = libxl_ctx_postfork(ctx);
-        if (rc) {
-            LOG("failed to reinitialise context after fork");
-            exit(-1);
-        }
+        postfork();
 
         if (asprintf(&name, "xl-%s", d_config.c_info.name) < 0) {
             LOG("Failed to allocate memory in asprintf");
-- 
1.7.2.5


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