[lttng-dev] [PATCH] Load modules through kmod

[David Goulet]

Merged!

I've made some basic syntax fix.

Big thanks for this!

Cheers!
David

On 04 Sep (10:30:53), Umut Tezduyar Lindskog wrote:
> Instead of forking processes, load modules through libkmod.
> 
> This adds an optional package dependency to kmod but can be
> disabled by --disable-kmod option in ./configure. If
> --enable-kmod option is given but no kmod is found, loading
> will happen by forking a process.
> 
> The startup time has decreased by %36 on our embedded mips
> product. The measurement is done by cgroup cpu shares.
> ---
>  configure.ac                      |   34 ++++++++++++++++++++++++
>  src/bin/lttng-sessiond/modprobe.c |   53 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 87 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index a8e04f5..fb0b03f 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -200,6 +200,32 @@ AC_CHECK_DECL([cmm_smp_mb__before_uatomic_or], [],
>          [AC_MSG_ERROR([liburcu $liburcu_version or newer is needed])], [[#include <urcu.h>]]
>  )
>  
> +# Check kmod library
> +AC_ARG_WITH(kmod-prefix,
> +  AS_HELP_STRING([--with-kmod-prefix=PATH],
> +                 [Specify the installation prefix of the kmod library.
> +	          Headers must be in PATH/include; libraries in PATH/lib.]),
> +		  [
> +		    CPPFLAGS="$CPPFLAGS -I${withval}/include"
> +		    LDFLAGS="$LDFLAGS -L${withval}/lib64 -L${withval}/lib"
> +		  ])
> +
> +AC_ARG_ENABLE(kmod,
> +	AS_HELP_STRING([--disable-kmod],[build without kmod support]),
> +	kmod_support=$enableval, kmod_support=yes)
> +
> +AS_IF([test "x$kmod_support" = "xyes"], [
> +	AC_CHECK_LIB([kmod], [kmod_module_probe_insert_module],
> +		[
> +			AC_DEFINE([HAVE_KMOD], [1], [has kmod support])
> +			LIBS="$LIBS -lkmod"
> +			kmod_found=yes
> +		],
> +		kmod_found=no
> +	)
> +])
> +AM_CONDITIONAL([HAVE_KMOD], [test "x$kmod_found" = xyes])
> +
>  AC_ARG_WITH(lttng-ust-prefix,
>    AS_HELP_STRING([--with-lttng-ust-prefix=PATH],
>                   [Specify the installation prefix of the lttng-ust library.
> @@ -483,6 +509,14 @@ done
>  AS_ECHO_N("Target architecture: ")
>  AS_ECHO($target_arch)
>  
> +# kmod enabled/disabled
> +AS_ECHO_N("kmod support: ")
> +AS_IF([test "x$kmod_found" = "xyes"],[
> +	AS_ECHO("Enabled")
> +],[
> +	AS_ECHO("Disabled")
> +])
> +
>  # LTTng-UST enabled/disabled
>  AS_ECHO_N("Lttng-UST support: ")
>  AS_IF([test "x$lttng_ust_support" = "xyes"],[
> diff --git a/src/bin/lttng-sessiond/modprobe.c b/src/bin/lttng-sessiond/modprobe.c
> index 3cc67f0..40a2ee0 100644
> --- a/src/bin/lttng-sessiond/modprobe.c
> +++ b/src/bin/lttng-sessiond/modprobe.c
> @@ -164,6 +164,58 @@ void modprobe_remove_lttng_all(void)
>  	modprobe_remove_lttng_control();
>  }
>  
> +#if HAVE_KMOD
> +#include <libkmod.h>
> +static void log_kmod(void *data, int priority, const char *file, int line,
> +		     const char *fn, const char *format, va_list args)
> +{
> +	char *str;
> +	if (vasprintf(&str, format, args) < 0)
> +		return;
> +	DBG("libkmod: %s", str);
> +	free(str);
> +}
> +static int modprobe_lttng(struct kern_modules_param *modules,
> +			  int entries, int required)
> +{
> +	int ret = 0, i;
> +	struct kmod_ctx *ctx;
> +
> +	ctx = kmod_new(NULL, NULL);
> +	if (!ctx) {
> +		PERROR("Unable to create kmod library context");
> +		ret = -ENOMEM;
> +		goto error;
> +	}
> +
> +	kmod_set_log_fn(ctx, log_kmod, NULL);
> +	kmod_load_resources(ctx);
> +
> +	for (i = 0; i < entries; i++) {
> +		struct kmod_module *mod = NULL;
> +
> +		ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
> +		if (ret < 0) {
> +			PERROR("Failed to create kmod module for %s", modules[i].name);
> +			goto error;
> +		}
> +
> +		ret = kmod_module_probe_insert_module(mod, KMOD_PROBE_IGNORE_LOADED, NULL, NULL, NULL, NULL);
> +		if (required && ret < 0) {
> +			ERR("Unable to load module %s", modules[i].name);
> +		} else {
> +			DBG("Modprobe successfully %s", modules[i].name);
> +		}
> +
> +		kmod_module_unref(mod);
> +	}
> +
> +error:
> +	if (ctx)
> +		kmod_unref(ctx);
> +	return ret;
> +}
> +#else
>  static int modprobe_lttng(struct kern_modules_param *modules,
>  			  int entries, int required)
>  {
> @@ -194,6 +246,7 @@ static int modprobe_lttng(struct kern_modules_param *modules,
>  error:
>  	return ret;
>  }
> +#endif
>  
>  /*
>   * Load control kernel module(s).
> -- 
> 1.7.10.4
> 
> 
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
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