The commit c3b1a35 "debugfs: make sure that debugfs_create_file() gets
used only for regulars" doesn't allow to use debugfs_create_file() for
dir. Use the version with "data", __debugfs_create_dir().
Signed-off-by: Hiroshi Doyu <[email protected]>
Reported-by: Laxman Dewangan <[email protected]>
---
drivers/iommu/tegra-smmu.c | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 5e51fb7..41aff7a 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -1035,9 +1035,7 @@ static void smmu_debugfs_create(struct smmu_device *smmu)
int i;
struct dentry *root;
- root = debugfs_create_file(dev_name(smmu->dev),
- S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
- NULL, smmu, NULL);
+ root = __debugfs_create_dir(dev_name(smmu->dev), NULL, smmu);
if (!root)
goto err_out;
smmu->debugfs_root = root;
--
1.7.5.4
Hi,
On Wed, Aug 08, 2012 at 09:24:33AM +0300, Hiroshi Doyu wrote:
> The commit c3b1a35 "debugfs: make sure that debugfs_create_file() gets
> used only for regulars" doesn't allow to use debugfs_create_file() for
> dir. Use the version with "data", __debugfs_create_dir().
>
> Signed-off-by: Hiroshi Doyu <[email protected]>
> Reported-by: Laxman Dewangan <[email protected]>
> ---
> drivers/iommu/tegra-smmu.c | 4 +---
> 1 files changed, 1 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 5e51fb7..41aff7a 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -1035,9 +1035,7 @@ static void smmu_debugfs_create(struct smmu_device *smmu)
> int i;
> struct dentry *root;
>
> - root = debugfs_create_file(dev_name(smmu->dev),
> - S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> - NULL, smmu, NULL);
> + root = __debugfs_create_dir(dev_name(smmu->dev), NULL, smmu);
why would the directory need extra data ? Looking in mainline,
tegra-smmu.c doesn't have any debugfs support, where can I see the
patches adding debugfs to tegra-smmu ? It doesn't look correct that the
directory will have a data field.
--
balbi
Hi,
On Wed, Aug 08, 2012 at 06:11:29PM +0300, Felipe Balbi wrote:
> Hi,
>
> On Wed, Aug 08, 2012 at 09:24:33AM +0300, Hiroshi Doyu wrote:
> > The commit c3b1a35 "debugfs: make sure that debugfs_create_file() gets
> > used only for regulars" doesn't allow to use debugfs_create_file() for
> > dir. Use the version with "data", __debugfs_create_dir().
> >
> > Signed-off-by: Hiroshi Doyu <[email protected]>
> > Reported-by: Laxman Dewangan <[email protected]>
> > ---
> > drivers/iommu/tegra-smmu.c | 4 +---
> > 1 files changed, 1 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> > index 5e51fb7..41aff7a 100644
> > --- a/drivers/iommu/tegra-smmu.c
> > +++ b/drivers/iommu/tegra-smmu.c
> > @@ -1035,9 +1035,7 @@ static void smmu_debugfs_create(struct smmu_device *smmu)
> > int i;
> > struct dentry *root;
> >
> > - root = debugfs_create_file(dev_name(smmu->dev),
> > - S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> > - NULL, smmu, NULL);
> > + root = __debugfs_create_dir(dev_name(smmu->dev), NULL, smmu);
>
> why would the directory need extra data ? Looking in mainline,
> tegra-smmu.c doesn't have any debugfs support, where can I see the
> patches adding debugfs to tegra-smmu ? It doesn't look correct that the
> directory will have a data field.
Looking at linux-next I found the commit which added it:
> @@ -892,6 +909,164 @@ static struct iommu_ops smmu_iommu_ops = {
> .pgsize_bitmap = SMMU_IOMMU_PGSIZES,
> };
>
> +/* Should be in the order of enum */
> +static const char * const smmu_debugfs_mc[] = { "mc", };
> +static const char * const smmu_debugfs_cache[] = { "tlb", "ptc", };
> +
> +static ssize_t smmu_debugfs_stats_write(struct file *file,
> + const char __user *buffer,
> + size_t count, loff_t *pos)
> +{
> + struct smmu_device *smmu;
> + struct dentry *dent;
> + int i, cache, mc;
> + enum {
> + _OFF = 0,
> + _ON,
> + _RESET,
> + };
> + const char * const command[] = {
> + [_OFF] = "off",
> + [_ON] = "on",
> + [_RESET] = "reset",
> + };
> + char str[] = "reset";
> + u32 val;
> + size_t offs;
> +
> + count = min_t(size_t, count, sizeof(str));
> + if (copy_from_user(str, buffer, count))
> + return -EINVAL;
> +
> + for (i = 0; i < ARRAY_SIZE(command); i++)
> + if (strncmp(str, command[i],
> + strlen(command[i])) == 0)
> + break;
> +
> + if (i == ARRAY_SIZE(command))
> + return -EINVAL;
> +
> + dent = file->f_dentry;
> + cache = (int)dent->d_inode->i_private;
cache you can figure out by the filename. In fact, it would be much
better to have tlc and ptc directories with a "status" filename which
you write ON/OFF/RESET or enable/disable/reset to trigger what you need.
For that to work, you should probably hold tlb and ptc on an array of
some sort, and pass those as data to their respective "status" files as
the data field. If tlb and ptc are properly defined structures which can
point back to smmu, then you have everything you need.
I mean something like:
struct smmu;
struct mc {
const char *name;
void __iomem *regs;
struct smmu *smmu;
};
struct smmu {
struct mc mc[2]; /*what does mc stand for ? memory controller ? */
...
};
debugfs_create_dir(smmu);
debugfs_create_dir(mc);
debugfs_create_dir(smmu->mc[1].name);
debugfs_create_dir(smmu->mc[2].name);
debugfs_create_file(&smmu->mc[1], status);
debugfs_create_file(&smmu->mc[2], status);
or something similar. You will avoid all the trickery you did here to
achieve what you need.
> + mc = (int)dent->d_parent->d_inode->i_private;
> + smmu = dent->d_parent->d_parent->d_inode->i_private;
> +
> + offs = SMMU_CACHE_CONFIG(cache);
> + val = smmu_read(smmu, offs);
> + switch (i) {
> + case _OFF:
> + val &= ~SMMU_CACHE_CONFIG_STATS_ENABLE;
> + val &= ~SMMU_CACHE_CONFIG_STATS_TEST;
> + smmu_write(smmu, val, offs);
> + break;
> + case _ON:
> + val |= SMMU_CACHE_CONFIG_STATS_ENABLE;
> + val &= ~SMMU_CACHE_CONFIG_STATS_TEST;
> + smmu_write(smmu, val, offs);
> + break;
> + case _RESET:
> + val |= SMMU_CACHE_CONFIG_STATS_TEST;
> + smmu_write(smmu, val, offs);
> + val &= ~SMMU_CACHE_CONFIG_STATS_TEST;
> + smmu_write(smmu, val, offs);
> + break;
> + default:
> + BUG();
> + break;
> + }
> +
> + dev_dbg(smmu->dev, "%s() %08x, %08x @%08x\n", __func__,
> + val, smmu_read(smmu, offs), offs);
> +
> + return count;
> +}
> +
> +static int smmu_debugfs_stats_show(struct seq_file *s, void *v)
> +{
> + struct smmu_device *smmu;
> + struct dentry *dent;
> + int i, cache, mc;
> + const char * const stats[] = { "hit", "miss", };
> +
> + dent = d_find_alias(s->private);
> + cache = (int)dent->d_inode->i_private;
> + mc = (int)dent->d_parent->d_inode->i_private;
> + smmu = dent->d_parent->d_parent->d_inode->i_private;
> +
> + for (i = 0; i < ARRAY_SIZE(stats); i++) {
> + u32 val;
> + size_t offs;
> +
> + offs = SMMU_STATS_CACHE_COUNT(mc, cache, i);
> + val = smmu_read(smmu, offs);
> + seq_printf(s, "%s:%08x ", stats[i], val);
> +
> + dev_dbg(smmu->dev, "%s() %s %08x @%08x\n", __func__,
> + stats[i], val, offs);
> + }
> + seq_printf(s, "\n");
> +
> + return 0;
> +}
> +
> +static int smmu_debugfs_stats_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, smmu_debugfs_stats_show, inode);
> +}
> +
> +static const struct file_operations smmu_debugfs_stats_fops = {
> + .open = smmu_debugfs_stats_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> + .write = smmu_debugfs_stats_write,
> +};
> +
> +static void smmu_debugfs_delete(struct smmu_device *smmu)
> +{
> + debugfs_remove_recursive(smmu->debugfs_root);
> +}
> +
> +static void smmu_debugfs_create(struct smmu_device *smmu)
> +{
> + int i;
> + struct dentry *root;
> +
> + root = debugfs_create_file(dev_name(smmu->dev),
> + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> + NULL, smmu, NULL);
directories don't need data. You don't even have a file_operations
structure so when exactly are you going to access the data ? What you
did above is actually wrong. You need to either patch this ASAP or drop
the patch you wrote and rewrite the whole debugfs support.
> + if (!root)
> + goto err_out;
> + smmu->debugfs_root = root;
> +
> + for (i = 0; i < ARRAY_SIZE(smmu_debugfs_mc); i++) {
> + int j;
> + struct dentry *mc;
> +
> + mc = debugfs_create_file(smmu_debugfs_mc[i],
> + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> + root, (void *)i, NULL);
likewise here. What would you use that index for ? Even if you were to
access it, how would you use it ? Not to mention that you never, ever
access the private_data of the directory :-)
Just convert these two to the proper debugfs_create_dir()
> + if (!mc)
> + goto err_out;
> +
> + for (j = 0; j < ARRAY_SIZE(smmu_debugfs_cache); j++) {
> + struct dentry *cache;
> +
> + cache = debugfs_create_file(smmu_debugfs_cache[j],
> + S_IWUGO | S_IRUGO, mc,
> + (void *)j,
> + &smmu_debugfs_stats_fops);
it would be far better to pass a structure which you actually need. In
this case 'smmu'. That will be a lot more useful for your code.
--
balbi
Hi,
Thank you for review. Already sent the another version of patch(v2:
*1), but I tried to answer the remaining questions inlined.....
On Wed, 8 Aug 2012 17:31:02 +0200
Felipe Balbi <[email protected]> wrote:
> * PGP Signed by an unknown key
>
> Hi,
>
> On Wed, Aug 08, 2012 at 06:11:29PM +0300, Felipe Balbi wrote:
> > Hi,
> >
> > On Wed, Aug 08, 2012 at 09:24:33AM +0300, Hiroshi Doyu wrote:
> > > The commit c3b1a35 "debugfs: make sure that debugfs_create_file() gets
> > > used only for regulars" doesn't allow to use debugfs_create_file() for
> > > dir. Use the version with "data", __debugfs_create_dir().
> > >
> > > Signed-off-by: Hiroshi Doyu <[email protected]>
> > > Reported-by: Laxman Dewangan <[email protected]>
> > > ---
> > > drivers/iommu/tegra-smmu.c | 4 +---
> > > 1 files changed, 1 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> > > index 5e51fb7..41aff7a 100644
> > > --- a/drivers/iommu/tegra-smmu.c
> > > +++ b/drivers/iommu/tegra-smmu.c
> > > @@ -1035,9 +1035,7 @@ static void smmu_debugfs_create(struct smmu_device *smmu)
> > > int i;
> > > struct dentry *root;
> > >
> > > - root = debugfs_create_file(dev_name(smmu->dev),
> > > - S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> > > - NULL, smmu, NULL);
> > > + root = __debugfs_create_dir(dev_name(smmu->dev), NULL, smmu);
> >
> > why would the directory need extra data ? Looking in mainline,
> > tegra-smmu.c doesn't have any debugfs support, where can I see the
> > patches adding debugfs to tegra-smmu ? It doesn't look correct that the
> > directory will have a data field.
>
> Looking at linux-next I found the commit which added it:
FYI: The original tegra smmu debugfs patch is:
http://lists.linuxfoundation.org/pipermail/iommu/2012-August/004507.html
> > @@ -892,6 +909,164 @@ static struct iommu_ops smmu_iommu_ops = {
> > .pgsize_bitmap = SMMU_IOMMU_PGSIZES,
> > };
> >
> > +/* Should be in the order of enum */
> > +static const char * const smmu_debugfs_mc[] = { "mc", };
> > +static const char * const smmu_debugfs_cache[] = { "tlb", "ptc", };
> > +
> > +static ssize_t smmu_debugfs_stats_write(struct file *file,
> > + const char __user *buffer,
> > + size_t count, loff_t *pos)
> > +{
> > + struct smmu_device *smmu;
> > + struct dentry *dent;
> > + int i, cache, mc;
> > + enum {
> > + _OFF = 0,
> > + _ON,
> > + _RESET,
> > + };
> > + const char * const command[] = {
> > + [_OFF] = "off",
> > + [_ON] = "on",
> > + [_RESET] = "reset",
> > + };
> > + char str[] = "reset";
> > + u32 val;
> > + size_t offs;
> > +
> > + count = min_t(size_t, count, sizeof(str));
> > + if (copy_from_user(str, buffer, count))
> > + return -EINVAL;
> > +
> > + for (i = 0; i < ARRAY_SIZE(command); i++)
> > + if (strncmp(str, command[i],
> > + strlen(command[i])) == 0)
> > + break;
> > +
> > + if (i == ARRAY_SIZE(command))
> > + return -EINVAL;
> > +
> > + dent = file->f_dentry;
> > + cache = (int)dent->d_inode->i_private;
>
> cache you can figure out by the filename. In fact, it would be much
> better to have tlc and ptc directories with a "status" filename which
> you write ON/OFF/RESET or enable/disable/reset to trigger what you need.
Actually I also considered {ptc,tlb} directories, but I thought that
those might be residual, or nested one more unnecessarily.
The current usage is:
$ echo "reset" > /sys/kernel/debug/smmu/mc/{tlb,ptc}
$ echo "on" > /sys/kernel/debug/smmu/mc/{tlb,ptc}
$ echo "off" > /sys/kernel/debug/smmu/mc/{tlb,ptc}
$ cat /sys/kernel/debug/smmu/mc/{tlb,ptc}
hit:0014910c miss:00014d22
The above format is:
hit:<HIT count><SPC>miss:<MISS count><SPC><CR+LF>
fscanf(fp, "hit:%lx miss:%lx", &hit, &miss);
If {ptc,tlb} was dir, the usage would be:
$ echo "reset" > /sys/kernel/debug/smmu/mc/{tlb,ptc}/status
$ echo "on" > /sys/kernel/debug/smmu/mc/{tlb,ptc}/status
$ echo "off" > /sys/kernel/debug/smmu/mc/{tlb,ptc}/status
$ cat /sys/kernel/debug/smmu/mc/{tlb,ptc}/data
hit:0014910c miss:00014d22
One advantage of dirs could be, you may be able to check the current
status by reading "status". It might be less likely read back
practically because if writing succeeded, the state should be what was
written.
> For that to work, you should probably hold tlb and ptc on an array of
> some sort, and pass those as data to their respective "status" files as
> the data field. If tlb and ptc are properly defined structures which can
> point back to smmu, then you have everything you need.
I also considered to introduce new structure like what you suggested
below, but I felt that the parent<-chile relationships are already in
directory hierarchy, and I wanted to avoid the residual data with
introducing new structures. Instead of introducing new structure,
those parent<-child relationships are always gotton from debugfs
directory hierarchy on demand. That was why I wanted to put data in
debugfs dir. With debugfs directories having private data, the
connections between entities would be kept in filesystem.
I've already sent another version of patch(v2, *1), which passes all
necessary data to a file, put in a structure. This v2 patch may be a
little bit simliear to what Felipe suggested below.
*1: http://lists.linuxfoundation.org/pipermail/iommu/2012-August/004535.html
> I mean something like:
>
> struct smmu;
>
> struct mc {
> const char *name;
> void __iomem *regs;
>
> struct smmu *smmu;
> };
>
> struct smmu {
> struct mc mc[2]; /*what does mc stand for ? memory controller ? */
>
> ...
> };
>
> debugfs_create_dir(smmu);
> debugfs_create_dir(mc);
> debugfs_create_dir(smmu->mc[1].name);
> debugfs_create_dir(smmu->mc[2].name);
> debugfs_create_file(&smmu->mc[1], status);
> debugfs_create_file(&smmu->mc[2], status);
>
> or something similar. You will avoid all the trickery you did here to
> achieve what you need.
>
> > + mc = (int)dent->d_parent->d_inode->i_private;
> > + smmu = dent->d_parent->d_parent->d_inode->i_private;
> > +
> > + offs = SMMU_CACHE_CONFIG(cache);
> > + val = smmu_read(smmu, offs);
> > + switch (i) {
> > + case _OFF:
> > + val &= ~SMMU_CACHE_CONFIG_STATS_ENABLE;
> > + val &= ~SMMU_CACHE_CONFIG_STATS_TEST;
> > + smmu_write(smmu, val, offs);
> > + break;
> > + case _ON:
> > + val |= SMMU_CACHE_CONFIG_STATS_ENABLE;
> > + val &= ~SMMU_CACHE_CONFIG_STATS_TEST;
> > + smmu_write(smmu, val, offs);
> > + break;
> > + case _RESET:
> > + val |= SMMU_CACHE_CONFIG_STATS_TEST;
> > + smmu_write(smmu, val, offs);
> > + val &= ~SMMU_CACHE_CONFIG_STATS_TEST;
> > + smmu_write(smmu, val, offs);
> > + break;
> > + default:
> > + BUG();
> > + break;
> > + }
> > +
> > + dev_dbg(smmu->dev, "%s() %08x, %08x @%08x\n", __func__,
> > + val, smmu_read(smmu, offs), offs);
> > +
> > + return count;
> > +}
> > +
> > +static int smmu_debugfs_stats_show(struct seq_file *s, void *v)
> > +{
> > + struct smmu_device *smmu;
> > + struct dentry *dent;
> > + int i, cache, mc;
> > + const char * const stats[] = { "hit", "miss", };
> > +
> > + dent = d_find_alias(s->private);
> > + cache = (int)dent->d_inode->i_private;
> > + mc = (int)dent->d_parent->d_inode->i_private;
> > + smmu = dent->d_parent->d_parent->d_inode->i_private;
> > +
> > + for (i = 0; i < ARRAY_SIZE(stats); i++) {
> > + u32 val;
> > + size_t offs;
> > +
> > + offs = SMMU_STATS_CACHE_COUNT(mc, cache, i);
> > + val = smmu_read(smmu, offs);
> > + seq_printf(s, "%s:%08x ", stats[i], val);
> > +
> > + dev_dbg(smmu->dev, "%s() %s %08x @%08x\n", __func__,
> > + stats[i], val, offs);
> > + }
> > + seq_printf(s, "\n");
> > +
> > + return 0;
> > +}
> > +
> > +static int smmu_debugfs_stats_open(struct inode *inode, struct file *file)
> > +{
> > + return single_open(file, smmu_debugfs_stats_show, inode);
> > +}
> > +
> > +static const struct file_operations smmu_debugfs_stats_fops = {
> > + .open = smmu_debugfs_stats_open,
> > + .read = seq_read,
> > + .llseek = seq_lseek,
> > + .release = single_release,
> > + .write = smmu_debugfs_stats_write,
> > +};
> > +
> > +static void smmu_debugfs_delete(struct smmu_device *smmu)
> > +{
> > + debugfs_remove_recursive(smmu->debugfs_root);
> > +}
> > +
> > +static void smmu_debugfs_create(struct smmu_device *smmu)
> > +{
> > + int i;
> > + struct dentry *root;
> > +
> > + root = debugfs_create_file(dev_name(smmu->dev),
> > + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> > + NULL, smmu, NULL);
>
> directories don't need data. You don't even have a file_operations
> structure so when exactly are you going to access the data ? What you
> did above is actually wrong. You need to either patch this ASAP or drop
> the patch you wrote and rewrite the whole debugfs support.
>
> > + if (!root)
> > + goto err_out;
> > + smmu->debugfs_root = root;
> > +
> > + for (i = 0; i < ARRAY_SIZE(smmu_debugfs_mc); i++) {
> > + int j;
> > + struct dentry *mc;
> > +
> > + mc = debugfs_create_file(smmu_debugfs_mc[i],
> > + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
> > + root, (void *)i, NULL);
>
> likewise here. What would you use that index for ? Even if you were to
> access it, how would you use it ? Not to mention that you never, ever
> access the private_data of the directory :-)
>
> Just convert these two to the proper debugfs_create_dir()
>
> > + if (!mc)
> > + goto err_out;
> > +
> > + for (j = 0; j < ARRAY_SIZE(smmu_debugfs_cache); j++) {
> > + struct dentry *cache;
> > +
> > + cache = debugfs_create_file(smmu_debugfs_cache[j],
> > + S_IWUGO | S_IRUGO, mc,
> > + (void *)j,
> > + &smmu_debugfs_stats_fops);
>
> it would be far better to pass a structure which you actually need. In
> this case 'smmu'. That will be a lot more useful for your code.
Hi,
On Wed, Aug 15, 2012 at 09:34:21AM +0300, Hiroshi Doyu wrote:
> > > @@ -892,6 +909,164 @@ static struct iommu_ops smmu_iommu_ops = {
> > > .pgsize_bitmap = SMMU_IOMMU_PGSIZES,
> > > };
> > >
> > > +/* Should be in the order of enum */
> > > +static const char * const smmu_debugfs_mc[] = { "mc", };
> > > +static const char * const smmu_debugfs_cache[] = { "tlb", "ptc", };
> > > +
> > > +static ssize_t smmu_debugfs_stats_write(struct file *file,
> > > + const char __user *buffer,
> > > + size_t count, loff_t *pos)
> > > +{
> > > + struct smmu_device *smmu;
> > > + struct dentry *dent;
> > > + int i, cache, mc;
> > > + enum {
> > > + _OFF = 0,
> > > + _ON,
> > > + _RESET,
> > > + };
> > > + const char * const command[] = {
> > > + [_OFF] = "off",
> > > + [_ON] = "on",
> > > + [_RESET] = "reset",
> > > + };
> > > + char str[] = "reset";
> > > + u32 val;
> > > + size_t offs;
> > > +
> > > + count = min_t(size_t, count, sizeof(str));
> > > + if (copy_from_user(str, buffer, count))
> > > + return -EINVAL;
> > > +
> > > + for (i = 0; i < ARRAY_SIZE(command); i++)
> > > + if (strncmp(str, command[i],
> > > + strlen(command[i])) == 0)
> > > + break;
> > > +
> > > + if (i == ARRAY_SIZE(command))
> > > + return -EINVAL;
> > > +
> > > + dent = file->f_dentry;
> > > + cache = (int)dent->d_inode->i_private;
> >
> > cache you can figure out by the filename. In fact, it would be much
> > better to have tlc and ptc directories with a "status" filename which
> > you write ON/OFF/RESET or enable/disable/reset to trigger what you need.
>
> Actually I also considered {ptc,tlb} directories, but I thought that
> those might be residual, or nested one more unnecessarily.
>
> The current usage is:
>
> $ echo "reset" > /sys/kernel/debug/smmu/mc/{tlb,ptc}
> $ echo "on" > /sys/kernel/debug/smmu/mc/{tlb,ptc}
> $ echo "off" > /sys/kernel/debug/smmu/mc/{tlb,ptc}
> $ cat /sys/kernel/debug/smmu/mc/{tlb,ptc}
> hit:0014910c miss:00014d22
>
> The above format is:
> hit:<HIT count><SPC>miss:<MISS count><SPC><CR+LF>
if you're just printing hit and miss count, wouldn't it be a bit more
human-friendly to print it in decimal rather than hex ? no strong
feelings against either way, just thought I'd mention it.
> fscanf(fp, "hit:%lx miss:%lx", &hit, &miss);
>
>
> If {ptc,tlb} was dir, the usage would be:
>
> $ echo "reset" > /sys/kernel/debug/smmu/mc/{tlb,ptc}/status
> $ echo "on" > /sys/kernel/debug/smmu/mc/{tlb,ptc}/status
> $ echo "off" > /sys/kernel/debug/smmu/mc/{tlb,ptc}/status
> $ cat /sys/kernel/debug/smmu/mc/{tlb,ptc}/data
> hit:0014910c miss:00014d22
>
> One advantage of dirs could be, you may be able to check the current
> status by reading "status". It might be less likely read back
> practically because if writing succeeded, the state should be what was
> written.
sure.
> > For that to work, you should probably hold tlb and ptc on an array of
> > some sort, and pass those as data to their respective "status" files as
> > the data field. If tlb and ptc are properly defined structures which can
> > point back to smmu, then you have everything you need.
>
> I also considered to introduce new structure like what you suggested
> below, but I felt that the parent<-chile relationships are already in
> directory hierarchy, and I wanted to avoid the residual data with
> introducing new structures. Instead of introducing new structure,
> those parent<-child relationships are always gotton from debugfs
> directory hierarchy on demand. That was why I wanted to put data in
> debugfs dir. With debugfs directories having private data, the
> connections between entities would be kept in filesystem.
fair enough.
> I've already sent another version of patch(v2, *1), which passes all
> necessary data to a file, put in a structure. This v2 patch may be a
> little bit simliear to what Felipe suggested below.
I looked over that, but I'm not sure you should introduce that
smmu_debugfs_info structure. Look at what we do on
drivers/usb/dwc3/debugfs.c, we don't add any extra structures for
debugfs, we use what the driver already has (struct dwc3-only,
currently).
If we were to add debgufs support for each USB endpoint, I would pass
struct dwc3_ep as data for the files. See that I would still be able to
access struct dwc3, should I need it, because struct dwc3_ep knows which
struct dwc3 it belongs to.
That's what I meant when I suggested adding more structures, not
something for debugfs-only, but something for the whole driver to use.
Just re-design the driver a little bit and you won't need to allocate
memory when creating debugfs directories, because the data you need is
already available.
--
balbi