[PATCHv2,5/9] debugfs: add get/set for atomic types
diff mbox series

Message ID 1357590280-31535-6-git-send-email-sjenning@linux.vnet.ibm.com
State New, archived
Headers show
Series
  • zswap: compressed swap caching
Related show

Commit Message

Seth Jennings Jan. 7, 2013, 8:24 p.m. UTC
debugfs currently lack the ability to create attributes
that set/get atomic_t values.

This patch adds support for this through a new
debugfs_create_atomic_t() function.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
---
 fs/debugfs/file.c       |   42 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/debugfs.h |    2 ++
 2 files changed, 44 insertions(+)

Comments

Greg Kroah-Hartman Jan. 7, 2013, 8:32 p.m. UTC | #1
On Mon, Jan 07, 2013 at 02:24:36PM -0600, Seth Jennings wrote:
> debugfs currently lack the ability to create attributes
> that set/get atomic_t values.

I hate to ask, but why would you ever want to do such a thing?

greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/
Seth Jennings Jan. 7, 2013, 8:41 p.m. UTC | #2
On 01/07/2013 02:32 PM, Greg Kroah-Hartman wrote:
> On Mon, Jan 07, 2013 at 02:24:36PM -0600, Seth Jennings wrote:
>> debugfs currently lack the ability to create attributes
>> that set/get atomic_t values.
> 
> I hate to ask, but why would you ever want to do such a thing?

There are a few atomic_t statistics in zswap that are valuable to have
in the debugfs attributes.  Rather than have non-atomic mirrors of all
of them, as is done in zcache right now (see
drivers/staging/ramster/zcache-main.c:131), I thought this to be a
cleaner solution.

Granted, I personally have no use for the setting part; only the
getting part.  I only included the setting operations to keep the
balance and conform with the rest of the debugfs implementation.

Seth

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/
Seth Jennings Jan. 25, 2013, 4:45 p.m. UTC | #3
On 01/07/2013 02:41 PM, Seth Jennings wrote:
> On 01/07/2013 02:32 PM, Greg Kroah-Hartman wrote:
>> On Mon, Jan 07, 2013 at 02:24:36PM -0600, Seth Jennings wrote:
>>> debugfs currently lack the ability to create attributes
>>> that set/get atomic_t values.
>>
>> I hate to ask, but why would you ever want to do such a thing?
> 
> There are a few atomic_t statistics in zswap that are valuable to have
> in the debugfs attributes.  Rather than have non-atomic mirrors of all
> of them, as is done in zcache right now (see
> drivers/staging/ramster/zcache-main.c:131), I thought this to be a
> cleaner solution.
> 
> Granted, I personally have no use for the setting part; only the
> getting part.  I only included the setting operations to keep the
> balance and conform with the rest of the debugfs implementation.

Greg, I never did get your ack or rejection here.  Are you ok with
this patch?

Thanks,
Seth

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/
Greg Kroah-Hartman Jan. 25, 2013, 9:35 p.m. UTC | #4
On Fri, Jan 25, 2013 at 10:45:04AM -0600, Seth Jennings wrote:
> On 01/07/2013 02:41 PM, Seth Jennings wrote:
> > On 01/07/2013 02:32 PM, Greg Kroah-Hartman wrote:
> >> On Mon, Jan 07, 2013 at 02:24:36PM -0600, Seth Jennings wrote:
> >>> debugfs currently lack the ability to create attributes
> >>> that set/get atomic_t values.
> >>
> >> I hate to ask, but why would you ever want to do such a thing?
> > 
> > There are a few atomic_t statistics in zswap that are valuable to have
> > in the debugfs attributes.  Rather than have non-atomic mirrors of all
> > of them, as is done in zcache right now (see
> > drivers/staging/ramster/zcache-main.c:131), I thought this to be a
> > cleaner solution.
> > 
> > Granted, I personally have no use for the setting part; only the
> > getting part.  I only included the setting operations to keep the
> > balance and conform with the rest of the debugfs implementation.
> 
> Greg, I never did get your ack or rejection here.  Are you ok with
> this patch?

Some patches you just hold your breath and hope the sender goes away and
never asks about again, this was one of them :)

Seriously, it's fine, feel free to take it through whatever tree it
depends on.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Patch
diff mbox series

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index c5ca6ae..fa26d5b 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -21,6 +21,7 @@ 
 #include <linux/debugfs.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/atomic.h>
 
 static ssize_t default_read_file(struct file *file, char __user *buf,
 				 size_t count, loff_t *ppos)
@@ -403,6 +404,47 @@  struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
 }
 EXPORT_SYMBOL_GPL(debugfs_create_size_t);
 
+static int debugfs_atomic_t_set(void *data, u64 val)
+{
+	atomic_set((atomic_t *)data, val);
+	return 0;
+}
+static int debugfs_atomic_t_get(void *data, u64 *val)
+{
+	*val = atomic_read((atomic_t *)data);
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
+			debugfs_atomic_t_set, "%llu\n");
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_ro, debugfs_atomic_t_get, NULL, "%llu\n");
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, "%llu\n");
+
+/**
+ * debugfs_create_atomic_t - create a debugfs file that is used to read and
+ * write an atomic_t value
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have
+ * @parent: a pointer to the parent dentry for this file.  This should be a
+ *          directory dentry if set.  If this parameter is %NULL, then the
+ *          file will be created in the root of the debugfs filesystem.
+ * @value: a pointer to the variable that the file should read to and write
+ *         from.
+ */
+struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
+				 struct dentry *parent, atomic_t *value)
+{
+	/* if there are no write bits set, make read only */
+	if (!(mode & S_IWUGO))
+		return debugfs_create_file(name, mode, parent, value,
+					&fops_atomic_t_ro);
+	/* if there are no read bits set, make write only */
+	if (!(mode & S_IRUGO))
+		return debugfs_create_file(name, mode, parent, value,
+					&fops_atomic_t_wo);
+
+	return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
+}
+EXPORT_SYMBOL_GPL(debugfs_create_atomic_t);
 
 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 			      size_t count, loff_t *ppos)
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 66c434f..51fea70 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -79,6 +79,8 @@  struct dentry *debugfs_create_x64(const char *name, umode_t mode,
 				  struct dentry *parent, u64 *value);
 struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
 				     struct dentry *parent, size_t *value);
+struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
+				     struct dentry *parent, atomic_t *value);
 struct dentry *debugfs_create_bool(const char *name, umode_t mode,
 				  struct dentry *parent, u32 *value);