Hi,
This patch performs a code cleanup against the expand_fdtable() and
expand_files() functions inside fs/file.c. It aims to make the flow of code
within these functions simpler and easier to understand, via added comments
and modest refactoring. The patch was generated against 2.6.18-rc5-mm1, and
was successfully run live. Please apply.
(I'm trying out KMail for this patch. I tested this mailer beforehand to make
sure the patch will come out unmangled, but, as with all things software,
success is far from guaranteed. :) Please yell if the patch is borked.)
Signed-off-by: Vadim Lobanov <[email protected]>
diff -Npru linux-a/fs/file.c linux-b/fs/file.c
--- linux-a/fs/file.c 2006-09-01 20:34:12.000000000 -0700
+++ linux-b/fs/file.c 2006-09-04 16:42:33.000000000 -0700
@@ -296,37 +296,30 @@ static int expand_fdtable(struct files_s
__releases(files->file_lock)
__acquires(files->file_lock)
{
- int error = 0;
- struct fdtable *fdt;
- struct fdtable *nfdt = NULL;
+ struct fdtable *new_fdt, *cur_fdt;
spin_unlock(&files->file_lock);
- nfdt = alloc_fdtable(nr);
- if (!nfdt) {
- error = -ENOMEM;
- spin_lock(&files->file_lock);
- goto out;
- }
-
+ new_fdt = alloc_fdtable(nr);
spin_lock(&files->file_lock);
- fdt = files_fdtable(files);
+ if (!new_fdt)
+ return -ENOMEM;
/*
- * Check again since another task may have expanded the
- * fd table while we dropped the lock
+ * Check again since another task may have expanded the fd table while
+ * we dropped the lock
*/
- if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
- copy_fdtable(nfdt, fdt);
+ cur_fdt = files_fdtable(files);
+ if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
+ /* Continue as planned */
+ copy_fdtable(new_fdt, cur_fdt);
+ rcu_assign_pointer(files->fdt, new_fdt);
+ free_fdtable(cur_fdt);
} else {
- /* Somebody expanded while we dropped file_lock */
+ /* Somebody else expanded, so undo our attempt */
spin_unlock(&files->file_lock);
- __free_fdtable(nfdt);
+ __free_fdtable(new_fdt);
spin_lock(&files->file_lock);
- goto out;
}
- rcu_assign_pointer(files->fdt, nfdt);
- free_fdtable(fdt);
-out:
- return error;
+ return 1;
}
/*
@@ -336,23 +329,19 @@ out:
*/
int expand_files(struct files_struct *files, int nr)
{
- int err, expand = 0;
struct fdtable *fdt;
fdt = files_fdtable(files);
- if (nr >= fdt->max_fdset || nr >= fdt->max_fds) {
- if (fdt->max_fdset >= NR_OPEN ||
- fdt->max_fds >= NR_OPEN || nr >= NR_OPEN) {
- err = -EMFILE;
- goto out;
- }
- expand = 1;
- if ((err = expand_fdtable(files, nr)))
- goto out;
- }
- err = expand;
-out:
- return err;
+ /* Do we need to expand? */
+ if (nr < fdt->max_fdset && nr < fdt->max_fds)
+ return 0;
+ /* Can we expand? */
+ if (fdt->max_fdset >= NR_OPEN || fdt->max_fds >= NR_OPEN ||
+ nr >= NR_OPEN)
+ return -EMFILE;
+
+ /* All good, so we try */
+ return expand_fdtable(files, nr);
}
static void __devinit fdtable_defer_list_init(int cpu)
On Mon, 4 Sep 2006 22:08:36 -0700 Vadim Lobanov wrote:
> Hi,
>
> This patch performs a code cleanup against the expand_fdtable() and
> expand_files() functions inside fs/file.c. It aims to make the flow of code
> within these functions simpler and easier to understand, via added comments
> and modest refactoring. The patch was generated against 2.6.18-rc5-mm1, and
> was successfully run live. Please apply.
>
> (I'm trying out KMail for this patch. I tested this mailer beforehand to make
> sure the patch will come out unmangled, but, as with all things software,
> success is far from guaranteed. :) Please yell if the patch is borked.)
It's not (mechanically) b0rked.
> Signed-off-by: Vadim Lobanov <[email protected]>
>
> diff -Npru linux-a/fs/file.c linux-b/fs/file.c
> --- linux-a/fs/file.c 2006-09-01 20:34:12.000000000 -0700
> +++ linux-b/fs/file.c 2006-09-04 16:42:33.000000000 -0700
> @@ -296,37 +296,30 @@ static int expand_fdtable(struct files_s
> __releases(files->file_lock)
> __acquires(files->file_lock)
> {
> - int error = 0;
> - struct fdtable *fdt;
> - struct fdtable *nfdt = NULL;
> + struct fdtable *new_fdt, *cur_fdt;
>
> spin_unlock(&files->file_lock);
> - nfdt = alloc_fdtable(nr);
> - if (!nfdt) {
> - error = -ENOMEM;
> - spin_lock(&files->file_lock);
> - goto out;
> - }
> -
> + new_fdt = alloc_fdtable(nr);
> spin_lock(&files->file_lock);
> - fdt = files_fdtable(files);
> + if (!new_fdt)
> + return -ENOMEM;
> /*
> - * Check again since another task may have expanded the
> - * fd table while we dropped the lock
> + * Check again since another task may have expanded the fd table while
> + * we dropped the lock
> */
> - if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
> - copy_fdtable(nfdt, fdt);
> + cur_fdt = files_fdtable(files);
> + if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
> + /* Continue as planned */
> + copy_fdtable(new_fdt, cur_fdt);
> + rcu_assign_pointer(files->fdt, new_fdt);
> + free_fdtable(cur_fdt);
> } else {
> - /* Somebody expanded while we dropped file_lock */
> + /* Somebody else expanded, so undo our attempt */
> spin_unlock(&files->file_lock);
> - __free_fdtable(nfdt);
> + __free_fdtable(new_fdt);
> spin_lock(&files->file_lock);
> - goto out;
> }
> - rcu_assign_pointer(files->fdt, nfdt);
> - free_fdtable(fdt);
> -out:
> - return error;
> + return 1;
This function didn't previously return a value of 1.
If it can do so now, please document it in the function comments
"header". Using kernel-doc would be good too.
> }
>
> /*
> @@ -336,23 +329,19 @@ out:
> */
> int expand_files(struct files_struct *files, int nr)
> {
> - int err, expand = 0;
> struct fdtable *fdt;
>
> fdt = files_fdtable(files);
> - if (nr >= fdt->max_fdset || nr >= fdt->max_fds) {
> - if (fdt->max_fdset >= NR_OPEN ||
> - fdt->max_fds >= NR_OPEN || nr >= NR_OPEN) {
> - err = -EMFILE;
> - goto out;
> - }
> - expand = 1;
> - if ((err = expand_fdtable(files, nr)))
> - goto out;
> - }
> - err = expand;
> -out:
> - return err;
> + /* Do we need to expand? */
> + if (nr < fdt->max_fdset && nr < fdt->max_fds)
> + return 0;
> + /* Can we expand? */
> + if (fdt->max_fdset >= NR_OPEN || fdt->max_fds >= NR_OPEN ||
> + nr >= NR_OPEN)
> + return -EMFILE;
> +
> + /* All good, so we try */
> + return expand_fdtable(files, nr);
> }
>
> static void __devinit fdtable_defer_list_init(int cpu)
---
~Randy
On Tuesday 05 September 2006 09:55, Randy.Dunlap wrote:
> On Mon, 4 Sep 2006 22:08:36 -0700 Vadim Lobanov wrote:
> > Hi,
> >
> > This patch performs a code cleanup against the expand_fdtable() and
> > expand_files() functions inside fs/file.c. It aims to make the flow of
> > code within these functions simpler and easier to understand, via added
> > comments and modest refactoring. The patch was generated against
> > 2.6.18-rc5-mm1, and was successfully run live. Please apply.
> >
> > (I'm trying out KMail for this patch. I tested this mailer beforehand to
> > make sure the patch will come out unmangled, but, as with all things
> > software, success is far from guaranteed. :) Please yell if the patch is
> > borked.)
>
> It's not (mechanically) b0rked.
>
> > Signed-off-by: Vadim Lobanov <[email protected]>
> >
> > diff -Npru linux-a/fs/file.c linux-b/fs/file.c
> > --- linux-a/fs/file.c 2006-09-01 20:34:12.000000000 -0700
> > +++ linux-b/fs/file.c 2006-09-04 16:42:33.000000000 -0700
> > @@ -296,37 +296,30 @@ static int expand_fdtable(struct files_s
> > __releases(files->file_lock)
> > __acquires(files->file_lock)
> > {
> > - int error = 0;
> > - struct fdtable *fdt;
> > - struct fdtable *nfdt = NULL;
> > + struct fdtable *new_fdt, *cur_fdt;
> >
> > spin_unlock(&files->file_lock);
> > - nfdt = alloc_fdtable(nr);
> > - if (!nfdt) {
> > - error = -ENOMEM;
> > - spin_lock(&files->file_lock);
> > - goto out;
> > - }
> > -
> > + new_fdt = alloc_fdtable(nr);
> > spin_lock(&files->file_lock);
> > - fdt = files_fdtable(files);
> > + if (!new_fdt)
> > + return -ENOMEM;
> > /*
> > - * Check again since another task may have expanded the
> > - * fd table while we dropped the lock
> > + * Check again since another task may have expanded the fd table while
> > + * we dropped the lock
> > */
> > - if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
> > - copy_fdtable(nfdt, fdt);
> > + cur_fdt = files_fdtable(files);
> > + if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
> > + /* Continue as planned */
> > + copy_fdtable(new_fdt, cur_fdt);
> > + rcu_assign_pointer(files->fdt, new_fdt);
> > + free_fdtable(cur_fdt);
> > } else {
> > - /* Somebody expanded while we dropped file_lock */
> > + /* Somebody else expanded, so undo our attempt */
> > spin_unlock(&files->file_lock);
> > - __free_fdtable(nfdt);
> > + __free_fdtable(new_fdt);
> > spin_lock(&files->file_lock);
> > - goto out;
> > }
> > - rcu_assign_pointer(files->fdt, nfdt);
> > - free_fdtable(fdt);
> > -out:
> > - return error;
> > + return 1;
>
> This function didn't previously return a value of 1.
> If it can do so now, please document it in the function comments
> "header". Using kernel-doc would be good too.
More comments on the function headers. Gotcha. Will resend.
The problem with kernel-doc in this particular instance is that none of the
other functions in that file have comments in that particular style; they all
currently use the mostly-unstructured C comments. If anything, it'd be far
simpler and cleaner to get this particular patch merged first, and then add
kernel-doc comments to _all_ the functions in this file at once in a later
patch.
>
> ---
> ~Randy
-- Vadim Lobanov
On Tue, 5 Sep 2006 11:56:49 -0700 Vadim Lobanov wrote:
> On Tuesday 05 September 2006 09:55, Randy.Dunlap wrote:
> > On Mon, 4 Sep 2006 22:08:36 -0700 Vadim Lobanov wrote:
> > > Hi,
> > >
> > > This patch performs a code cleanup against the expand_fdtable() and
> > > expand_files() functions inside fs/file.c. It aims to make the flow of
> > > code within these functions simpler and easier to understand, via added
> > > comments and modest refactoring. The patch was generated against
> > > 2.6.18-rc5-mm1, and was successfully run live. Please apply.
> > >
> > > (I'm trying out KMail for this patch. I tested this mailer beforehand to
> > > make sure the patch will come out unmangled, but, as with all things
> > > software, success is far from guaranteed. :) Please yell if the patch is
> > > borked.)
> >
> > It's not (mechanically) b0rked.
> >
> > > Signed-off-by: Vadim Lobanov <[email protected]>
> > >
> > > diff -Npru linux-a/fs/file.c linux-b/fs/file.c
> > > --- linux-a/fs/file.c 2006-09-01 20:34:12.000000000 -0700
> > > +++ linux-b/fs/file.c 2006-09-04 16:42:33.000000000 -0700
> > > @@ -296,37 +296,30 @@ static int expand_fdtable(struct files_s
> > > __releases(files->file_lock)
> > > __acquires(files->file_lock)
> > > {
> > > - int error = 0;
> > > - struct fdtable *fdt;
> > > - struct fdtable *nfdt = NULL;
> > > + struct fdtable *new_fdt, *cur_fdt;
> > >
> > > spin_unlock(&files->file_lock);
> > > - nfdt = alloc_fdtable(nr);
> > > - if (!nfdt) {
> > > - error = -ENOMEM;
> > > - spin_lock(&files->file_lock);
> > > - goto out;
> > > - }
> > > -
> > > + new_fdt = alloc_fdtable(nr);
> > > spin_lock(&files->file_lock);
> > > - fdt = files_fdtable(files);
> > > + if (!new_fdt)
> > > + return -ENOMEM;
> > > /*
> > > - * Check again since another task may have expanded the
> > > - * fd table while we dropped the lock
> > > + * Check again since another task may have expanded the fd table while
> > > + * we dropped the lock
> > > */
> > > - if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
> > > - copy_fdtable(nfdt, fdt);
> > > + cur_fdt = files_fdtable(files);
> > > + if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
> > > + /* Continue as planned */
> > > + copy_fdtable(new_fdt, cur_fdt);
> > > + rcu_assign_pointer(files->fdt, new_fdt);
> > > + free_fdtable(cur_fdt);
> > > } else {
> > > - /* Somebody expanded while we dropped file_lock */
> > > + /* Somebody else expanded, so undo our attempt */
> > > spin_unlock(&files->file_lock);
> > > - __free_fdtable(nfdt);
> > > + __free_fdtable(new_fdt);
> > > spin_lock(&files->file_lock);
> > > - goto out;
> > > }
> > > - rcu_assign_pointer(files->fdt, nfdt);
> > > - free_fdtable(fdt);
> > > -out:
> > > - return error;
> > > + return 1;
> >
> > This function didn't previously return a value of 1.
> > If it can do so now, please document it in the function comments
> > "header". Using kernel-doc would be good too.
>
> More comments on the function headers. Gotcha. Will resend.
>
> The problem with kernel-doc in this particular instance is that none of the
> other functions in that file have comments in that particular style; they all
> currently use the mostly-unstructured C comments. If anything, it'd be far
> simpler and cleaner to get this particular patch merged first, and then add
> kernel-doc comments to _all_ the functions in this file at once in a later
> patch.
Sure. The kernel-doc comment was certainly secondary.
---
~Randy