[Xen-devel] [PATCH v2] xenstore: add memory allocation debugging capability

[Juergen Gross <jgross@xxxxxxxx>]

Add support for debugging memory allocation statistics to xenstored.
Specifying "-M <file>" on the command line will enable the feature.
Whenever xenstored receives SIGUSR1 it will dump out a full talloc
report to <file>. This helps finding e.g. memory leaks in xenstored.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
To be applied on top of my "xenstore: fix memory leak of xenstored"
series. In fact this patch was used to find the problem the series
fixed and I used it to verify the patches are working.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 tools/xenstore/xenstored_core.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 51fb0b3..8bb1eff 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -81,6 +81,7 @@ static int reopen_log_pipe[2];
 static int reopen_log_pipe0_pollfd_idx = -1;
 static char *tracefile = NULL;
 static TDB_CONTEXT *tdb_ctx = NULL;
+static bool trigger_talloc_report = false;
 
 static void corrupt(struct connection *conn, const char *fmt, ...);
 static void check_store(void);
@@ -1743,6 +1744,10 @@ static void init_sockets(int **psock, int **pro_sock)
        static int minus_one = -1;
        *psock = *pro_sock = &minus_one;
 }
+
+static void do_talloc_report(int sig)
+{
+}
 #else
 static int destroy_fd(void *_fd)
 {
@@ -1876,6 +1881,11 @@ static void init_sockets(int **psock, int **pro_sock)
 
 
 }
+
+static void do_talloc_report(int sig)
+{
+       trigger_talloc_report = true;
+}
 #endif
 
 static void usage(void)
@@ -1901,6 +1911,7 @@ static void usage(void)
 "                          the store is corrupted (debug only),\n"
 "  -I, --internal-db       store database in memory, not on disk\n"
 "  -L, --preserve-local    to request that /local is preserved on start-up,\n"
+"  -M, --memory-debug <file>  support memory debugging to file,\n"
 "  -V, --verbose           to request verbose execution.\n");
 }
 
@@ -1923,6 +1934,7 @@ static struct option options[] = {
        { "internal-db", 0, NULL, 'I' },
        { "verbose", 0, NULL, 'V' },
        { "watch-nb", 1, NULL, 'W' },
+       { "memory-debug", 1, NULL, 'M' },
        { NULL, 0, NULL, 0 } };
 
 extern void dump_conn(struct connection *conn); 
@@ -1938,12 +1950,13 @@ int main(int argc, char *argv[])
        bool outputpid = false;
        bool no_domain_init = false;
        const char *pidfile = NULL;
+       const char *memfile = NULL;
        int timeout;
 #if defined(XEN_SYSTEMD_ENABLED)
        bool systemd;
 #endif
 
-       while ((opt = getopt_long(argc, argv, "DE:F:HNPS:t:T:RLVW:", options,
+       while ((opt = getopt_long(argc, argv, "DE:F:HNPS:t:T:RLVW:M:", options,
                                  NULL)) != -1) {
                switch (opt) {
                case 'D':
@@ -1997,6 +2010,9 @@ int main(int argc, char *argv[])
                case 'p':
                        priv_domid = strtol(optarg, NULL, 10);
                        break;
+               case 'M':
+                       memfile = optarg;
+                       break;
                }
        }
        if (optind != argc)
@@ -2033,6 +2049,11 @@ int main(int argc, char *argv[])
        /* Don't kill us with SIGPIPE. */
        signal(SIGPIPE, SIG_IGN);
 
+       if (memfile) {
+               talloc_enable_null_tracking();
+               signal(SIGUSR1, do_talloc_report);
+       }
+
 #if defined(XEN_SYSTEMD_ENABLED)
        if (!systemd)
 #endif
@@ -2079,6 +2100,17 @@ int main(int argc, char *argv[])
        for (;;) {
                struct connection *conn, *next;
 
+               if (trigger_talloc_report) {
+                       FILE *out;
+
+                       trigger_talloc_report = false;
+                       out = fopen(memfile, "a");
+                       if (out) {
+                               talloc_report_full(NULL, out);
+                               fclose(out);
+                       }
+               }
+
                if (poll(fds, nr_fds, timeout) < 0) {
                        if (errno == EINTR)
                                continue;
-- 
2.6.6


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