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Message-ID: <4CB31592.2080508@us.ibm.com>
Date: Mon, 11 Oct 2010 08:48:02 -0500
From: Maynard Johnson <maynardj@...ibm.com>
To: Robert Richter <robert.richter@....com>
CC: LKML <linux-kernel@...r.kernel.org>,
oprofile-list <oprofile-list@...ts.sourceforge.net>,
William Cohen <wcohen@...hat.com>,
"Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
Subject: Re: [PATCH] oprofile: disable write access to oprofilefs while profiler
is running
On 10/05/2010 11:33 AM, Robert Richter wrote:
> On 05.10.10 06:36:57, Robert Richter wrote:
>> Oprofile counters are setup when profiling is disabled. Thus, writing
>> to oprofilefs has no immediate effect. Changes are updated only after
>> oprofile is reenabled.
Robert, I don't have any issue with this patch except I'm not sure what problem
it's fixing. From my read of oprofile userland code, I don't see where
profiling parameters are ever written to oprofilefs when profiling is active.
Is your patch intended to guard against potential non-intentional cases
occurring in userland code? Or is there some case existing right now?
-Maynard
>>
>> To keep userland and kernel states synchronized, we now allow
>> configuration of oprofile only if profiling is disabled. In this case
>> it checks if the profiler is running and then disables write access to
>> oprofilefs by returning -EBUSY. The change should be backward
>> compatible with current oprofile userland daemon.
>>
>> Cc: Maynard Johnson<maynardj@...ibm.com>
>> Cc: William Cohen<wcohen@...hat.com>
>> Cc: Suravee Suthikulpanit<suravee.suthikulpanit@....com>
>> Signed-off-by: Robert Richter<robert.richter@....com>
>> ---
>> drivers/oprofile/oprof.c | 19 +++++--------------
>> drivers/oprofile/oprof.h | 2 +-
>> drivers/oprofile/oprofile_files.c | 7 +++++--
>> drivers/oprofile/oprofilefs.c | 8 ++++++--
>> 4 files changed, 17 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
>> index b4a6857..a7ab09e 100644
>> --- a/drivers/oprofile/oprof.c
>> +++ b/drivers/oprofile/oprof.c
>> @@ -225,26 +225,17 @@ post_sync:
>> mutex_unlock(&start_mutex);
>> }
>>
>> -int oprofile_set_backtrace(unsigned long val)
>> +int oprofile_set_ulong(unsigned long *addr, unsigned long val)
>> {
>> - int err = 0;
>> + int err = -EBUSY;
>>
>> mutex_lock(&start_mutex);
>> -
>> if (oprofile_started) {
>
> I did a late change which I never should do. It should be:
>
> if (!oprofile_started) ...
>
> The concept remains the same.
>
> Updated patch below.
>
> Sorry,
>
> -Robert
>
>> - err = -EBUSY;
>> - goto out;
>> - }
>> -
>> - if (!oprofile_ops.backtrace) {
>> - err = -EINVAL;
>> - goto out;
>> + *addr = val;
>> + err = 0;
>> }
>> -
>> - oprofile_backtrace_depth = val;
>> -
>> -out:
>> mutex_unlock(&start_mutex);
>> +
>> return err;
>> }
>
> --
>
> From 2d5710a2850eec24c54a1338ae5986963928cf8a Mon Sep 17 00:00:00 2001
> From: Robert Richter<robert.richter@....com>
> Date: Mon, 4 Oct 2010 21:09:36 +0200
> Subject: [PATCH] oprofile: disable write access to oprofilefs while profiler is running
>
> Oprofile counters are setup when profiling is disabled. Thus, writing
> to oprofilefs has no immediate effect. Changes are updated only after
> oprofile is reenabled.
>
> To keep userland and kernel states synchronized, we now allow
> configuration of oprofile only if profiling is disabled. In this case
> it checks if the profiler is running and then disables write access to
> oprofilefs by returning -EBUSY. The change should be backward
> compatible with current oprofile userland daemon.
>
> Cc: Maynard Johnson<maynardj@...ibm.com>
> Cc: William Cohen<wcohen@...hat.com>
> Cc: Suravee Suthikulpanit<suravee.suthikulpanit@....com>
> Signed-off-by: Robert Richter<robert.richter@....com>
> ---
> drivers/oprofile/oprof.c | 21 ++++++---------------
> drivers/oprofile/oprof.h | 2 +-
> drivers/oprofile/oprofile_files.c | 7 +++++--
> drivers/oprofile/oprofilefs.c | 8 ++++++--
> 4 files changed, 18 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
> index b4a6857..f9bda64 100644
> --- a/drivers/oprofile/oprof.c
> +++ b/drivers/oprofile/oprof.c
> @@ -225,26 +225,17 @@ post_sync:
> mutex_unlock(&start_mutex);
> }
>
> -int oprofile_set_backtrace(unsigned long val)
> +int oprofile_set_ulong(unsigned long *addr, unsigned long val)
> {
> - int err = 0;
> + int err = -EBUSY;
>
> mutex_lock(&start_mutex);
> -
> - if (oprofile_started) {
> - err = -EBUSY;
> - goto out;
> + if (!oprofile_started) {
> + *addr = val;
> + err = 0;
> }
> -
> - if (!oprofile_ops.backtrace) {
> - err = -EINVAL;
> - goto out;
> - }
> -
> - oprofile_backtrace_depth = val;
> -
> -out:
> mutex_unlock(&start_mutex);
> +
> return err;
> }
>
> diff --git a/drivers/oprofile/oprof.h b/drivers/oprofile/oprof.h
> index 47e12cb..177b73d 100644
> --- a/drivers/oprofile/oprof.h
> +++ b/drivers/oprofile/oprof.h
> @@ -37,7 +37,7 @@ void oprofile_create_files(struct super_block *sb, struct dentry *root);
> int oprofile_timer_init(struct oprofile_operations *ops);
> void oprofile_timer_exit(void);
>
> -int oprofile_set_backtrace(unsigned long depth);
> +int oprofile_set_ulong(unsigned long *addr, unsigned long val);
> int oprofile_set_timeout(unsigned long time);
>
> #endif /* OPROF_H */
> diff --git a/drivers/oprofile/oprofile_files.c b/drivers/oprofile/oprofile_files.c
> index bbd7516..ccf099e 100644
> --- a/drivers/oprofile/oprofile_files.c
> +++ b/drivers/oprofile/oprofile_files.c
> @@ -79,14 +79,17 @@ static ssize_t depth_write(struct file *file, char const __user *buf, size_t cou
> if (*offset)
> return -EINVAL;
>
> + if (!oprofile_ops.backtrace)
> + return -EINVAL;
> +
> retval = oprofilefs_ulong_from_user(&val, buf, count);
> if (retval)
> return retval;
>
> - retval = oprofile_set_backtrace(val);
> -
> + retval = oprofile_set_ulong(&oprofile_backtrace_depth, val);
> if (retval)
> return retval;
> +
> return count;
> }
>
> diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c
> index 789a1a8..1944621 100644
> --- a/drivers/oprofile/oprofilefs.c
> +++ b/drivers/oprofile/oprofilefs.c
> @@ -91,16 +91,20 @@ static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count
>
> static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
> {
> - unsigned long *value = file->private_data;
> + unsigned long value;
> int retval;
>
> if (*offset)
> return -EINVAL;
>
> - retval = oprofilefs_ulong_from_user(value, buf, count);
> + retval = oprofilefs_ulong_from_user(&value, buf, count);
> + if (retval)
> + return retval;
>
> + retval = oprofile_set_ulong(file->private_data, value);
> if (retval)
> return retval;
> +
> return count;
> }
>
--
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