[lttng-dev] [PATCH lttng-modules] Clean up using global_dirty_limit wrapper for writeback probe

[Mathieu Desnoyers]

* Andrew Gabbasov (andrew_gabbasov at mentor.com) wrote:
> Move the wrapper around reading of global_dirty_limit to /wrapper/ directory.
> Introduce a new kallsyms_lookup_dataptr function for obtaining the address
> unchanged and use it in global_dirty_limit wrapper.
> Since the data address is available only if CONFIG_KALLSYMS_ALL is set,
> omit the whole probe from building if this config is missing.

merged, thanks!

Mathieu

> 
> Signed-off-by: Andrew Gabbasov <andrew_gabbasov at mentor.com>
> ---
>  probes/Makefile                |    2 ++
>  probes/lttng-probe-writeback.c |   19 ++-----------
>  wrapper/kallsyms.h             |    6 ++++
>  wrapper/writeback.h            |   61 ++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 71 insertions(+), 17 deletions(-)
>  create mode 100644 wrapper/writeback.h
> 
> diff --git a/probes/Makefile b/probes/Makefile
> index 088cd5f..08adad5 100644
> --- a/probes/Makefile
> +++ b/probes/Makefile
> @@ -189,10 +189,12 @@ endif
>  
>  obj-m += lttng-probe-workqueue.o
>  
> +ifneq ($(CONFIG_KALLSYMS_ALL),)
>  obj-m +=  $(shell \
>  	if [ $(VERSION) -ge 3 \
>  		-o \( $(VERSION) -eq 2 -a $(PATCHLEVEL) -ge 6 -a $(SUBLEVEL) -ge 36 \) ] ; then \
>  		echo "lttng-probe-writeback.o" ; fi;)
> +endif
>  
>  
>  ifneq ($(CONFIG_KPROBES),)
> diff --git a/probes/lttng-probe-writeback.c b/probes/lttng-probe-writeback.c
> index 0a5c022..5e421e5 100644
> --- a/probes/lttng-probe-writeback.c
> +++ b/probes/lttng-probe-writeback.c
> @@ -32,27 +32,12 @@
>  #include <trace/events/writeback.h>
>  
>  #include "../lttng-kernel-version.h"
> +#include "../wrapper/writeback.h"
>  
>  /* #if <check version number if global_dirty_limit will be exported> */
> -#ifdef CONFIG_KALLSYMS
> -#include "../wrapper/kallsyms.h"
>  
> -static unsigned long *wrapper_global_dirty_limit_sym = 0;
> -static inline
> -unsigned long wrapper_global_dirty_limit(void)
> -{
> -	if (!wrapper_global_dirty_limit_sym)
> -		wrapper_global_dirty_limit_sym =
> -			(void *)kallsyms_lookup_funcptr("global_dirty_limit");
> -	if (wrapper_global_dirty_limit_sym)
> -		return *wrapper_global_dirty_limit_sym;
> -	else {
> -		printk(KERN_WARNING "LTTng: global_dirty_limit symbol lookup failed.\n");
> -		return 0;
> -	}
> -}
>  #define global_dirty_limit wrapper_global_dirty_limit()
> -#endif
> +
>  /* #endif <check version number> */
>  
>  /*
> diff --git a/wrapper/kallsyms.h b/wrapper/kallsyms.h
> index f07788a..ad9e1f2 100644
> --- a/wrapper/kallsyms.h
> +++ b/wrapper/kallsyms.h
> @@ -42,4 +42,10 @@ unsigned long kallsyms_lookup_funcptr(const char *name)
>  #endif
>  	return addr;
>  }
> +
> +static inline
> +unsigned long kallsyms_lookup_dataptr(const char *name)
> +{
> +	return kallsyms_lookup_name(name);
> +}
>  #endif /* _LTTNG_WRAPPER_KALLSYMS_H */
> diff --git a/wrapper/writeback.h b/wrapper/writeback.h
> new file mode 100644
> index 0000000..818ddd6
> --- /dev/null
> +++ b/wrapper/writeback.h
> @@ -0,0 +1,61 @@
> +#ifndef _LTTNG_WRAPPER_WRITEBACK_H
> +#define _LTTNG_WRAPPER_WRITEBACK_H
> +
> +/*
> + * wrapper/writeback.h
> + *
> + * wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL
> + * to get its address when available, else we need to have a kernel that
> + * exports this variable to GPL modules.
> + *
> + * Copyright (C) 2013 Mentor Graphics Corp.
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; only
> + * version 2.1 of the License.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifdef CONFIG_KALLSYMS_ALL
> +
> +#include <linux/kallsyms.h>
> +#include "kallsyms.h"
> +
> +static unsigned long *global_dirty_limit_sym = 0;
> +
> +static inline
> +unsigned long wrapper_global_dirty_limit(void)
> +{
> +	if (!global_dirty_limit_sym)
> +		global_dirty_limit_sym =
> +			(void *)kallsyms_lookup_dataptr("global_dirty_limit");
> +	if (global_dirty_limit_sym)
> +		return *global_dirty_limit_sym;
> +	else {
> +		printk(KERN_WARNING "LTTng: global_dirty_limit symbol lookup failed.\n");
> +		return 0;
> +	}
> +}
> +
> +#else
> +
> +#include <linux/writeback.h>
> +
> +static inline
> +unsigned long wrapper_global_dirty_limit(void)
> +{
> +	return global_dirty_limit;
> +}
> +
> +#endif
> +
> +#endif /* _LTTNG_WRAPPER_WRITEBACK_H */
> -- 
> 1.7.10.4
> 
> 
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com