Re: [PATCH v3] plugins/syscall: Added a table-like summary output

[Alex Bennée]

Mahmoud Mandour <ma.mandourr@gmail.com> writes:

> Added a table-like output which contains the total number of calls
> for each used syscall along with the number of errors that occurred.
>
> Per-call tracing is still available through supplying the argument
> ``print`` to the plugin.
>
> Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
> ---
<snip>
> +
> +void print_entry(gpointer val, gpointer user_data)
>  {
>      g_autofree gchar *out;
> -    out = g_strdup_printf("syscall #%" PRIi64 " returned -> %" PRIi64 "\n",
> -            num, ret);
> +    SyscallStats *entry = (SyscallStats *) val;
> +    int64_t syscall_num = entry->num;
> +    out = g_strdup_printf(
> +        "%-13" PRIi64 "%-6" PRIi64 " %" PRIi64 "\n",
> +        syscall_num, entry->calls, entry->errors);
>      qemu_plugin_outs(out);
>  }

This still fails to compile due to a missing static:

[2/10] Compiling C object tests/plugin/libsyscall.so.p/syscall.c.o
FAILED: tests/plugin/libsyscall.so.p/syscall.c.o
cc -Itests/plugin/libsyscall.so.p -Itests/plugin -I../../tests/plugin 
-I../../include/qemu -I/usr/include/glib-2.0 
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fdiagnostics-color=auto -pipe 
-Wall -Winvalid-pch -Werror -std=gnu99 -O2 -g -isystem 
/home/alex/lsrc/qemu.git/linux-headers -isystem linux-headers -iquote . -iquote 
/home/alex/lsrc/qemu.git -iquote /home/alex/lsrc/qemu.git/include -iquote 
/home/alex/lsrc/qemu.git/disas/libvixl -iquote 
/home/alex/lsrc/qemu.git/tcg/i386 -pthread -U_FORTIFY_SOURCE 
-D_FORTIFY_SOURCE=2 -m64 -mcx16 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 
-D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef 
-Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv 
-Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs 
-Wendif-labels -Wexpansion-to-defined -Wimplicit-fallthrough=2 
-Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi 
-fstack-protector-strong -DLEGACY_RDMA_REG_MR -fPIC -MD -MQ 
tests/plugin/libsyscall.so.p/syscall.c.o -MF 
tests/plugin/libsyscall.so.p/syscall.c.o.d -o 
tests/plugin/libsyscall.so.p/syscall.c.o -c ../../tests/plugin/syscall.c
../../tests/plugin/syscall.c:80:6: error: no previous prototype for 
‘print_entry’ [-Werror=missing-prototypes]
 void print_entry(gpointer val, gpointer user_data)
      ^~~~~~~~~~~
cc1: all warnings being treated as errors
ninja: build stopped: subcommand failed.
make: *** [Makefile:152: run-ninja] Error 1

>  
> +static gint comp_func(gconstpointer ea, gconstpointer eb)
> +{
> +    SyscallStats *ent_a = (SyscallStats *) ea;
> +    SyscallStats *ent_b = (SyscallStats *) eb;
> +
> +    return ent_a->calls > ent_b->calls ? -1 : 1;
> +}
> +
>  /* ************************************************************************* 
> */
> +static void plugin_exit(qemu_plugin_id_t id, void *p)
> +{
> +    if (!statistics) {
> +        return;
> +    }
> +
> +    g_mutex_lock(&lock);
> +    GList *entries = g_hash_table_get_values(statistics);
> +    entries = g_list_sort(entries, comp_func);
> +    qemu_plugin_outs("syscall no.  calls  errors\n");
>  
> -static void plugin_exit(qemu_plugin_id_t id, void *p) {}
> +    g_list_foreach(entries, print_entry, NULL);
> +
> +    g_list_free(entries);
> +    g_hash_table_destroy(statistics);
> +    g_mutex_unlock(&lock);
> +}

Hmm it looks like we see multiple plugin_exit's when running multiple
threads:

  ./qemu-aarch64 -d plugin -D output -plugin ./tests/plugin/libsyscall.so 
./tests/tcg/aarch64-linux-user/linux-test

I don't see it with testthread or the new signals test though which is
confusing. Something linux-test is doing must be different.

>  
>  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
>                                             const qemu_info_t *info,
>                                             int argc, char **argv)
>  {
> +    if (argc == 0) {
> +        statistics = g_hash_table_new_full(NULL, g_direct_equal, NULL, 
> g_free);
> +    } else {
> +        for (int i = 0; i < argc; i++) {
> +            if (g_strcmp0(argv[i], "print") != 0) {
> +                fprintf(stderr, "unsupported argument: %s\n", argv[i]);
> +                return -1;
> +            }
> +        }
> +    }
> +
>      qemu_plugin_register_vcpu_syscall_cb(id, vcpu_syscall);
>      qemu_plugin_register_vcpu_syscall_ret_cb(id, vcpu_syscall_ret);
>      qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);

Otherwise looking pretty good - certainly a more useful default ;-)

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


-- 
Alex Bennée