sysctl_nr_open_min, sysctl_nr_open_max variables are really hard limits
on fs.nr_open sysctl, they aren't interesting to the rest of the code
and are constants (sysctl_nr_open is not constant obviously).
Signed-off-by: Alexey Dobriyan <[email protected]>
---
fs/file.c | 5 -----
fs/file_table.c | 10 ++++++++--
include/linux/file.h | 2 --
3 files changed, 8 insertions(+), 9 deletions(-)
--- a/fs/file.c
+++ b/fs/file.c
@@ -25,11 +25,6 @@
#include "internal.h"
unsigned int sysctl_nr_open __read_mostly = 1024*1024;
-unsigned int sysctl_nr_open_min = BITS_PER_LONG;
-/* our min() is unusable in constant expressions ;-/ */
-#define __const_min(x, y) ((x) < (y) ? (x) : (y))
-unsigned int sysctl_nr_open_max =
- __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
static void __free_fdtable(struct fdtable *fdt)
{
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -111,6 +111,12 @@ static int proc_nr_files(struct ctl_table *table, int write, void *buffer,
return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
+static const unsigned int sysctl_nr_open_min = BITS_PER_LONG;
+/* our min() is unusable in constant expressions ;-/ */
+#define __const_min(x, y) ((x) < (y) ? (x) : (y))
+static const unsigned int sysctl_nr_open_max =
+ __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
+
static struct ctl_table fs_stat_sysctls[] = {
{
.procname = "file-nr",
@@ -134,8 +140,8 @@ static struct ctl_table fs_stat_sysctls[] = {
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
- .extra1 = &sysctl_nr_open_min,
- .extra2 = &sysctl_nr_open_max,
+ .extra1 = (void *)&sysctl_nr_open_min,
+ .extra2 = (void *)&sysctl_nr_open_max,
},
{ }
};
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -113,6 +113,4 @@ int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags);
extern void flush_delayed_fput(void);
extern void __fput_sync(struct file *);
-extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max;
-
#endif /* __LINUX_FILE_H */
From: Alexey Dobriyan
> Sent: 11 October 2023 19:24
>
> sysctl_nr_open_min, sysctl_nr_open_max variables are really hard limits
> on fs.nr_open sysctl, they aren't interesting to the rest of the code
> and are constants (sysctl_nr_open is not constant obviously).
>
> Signed-off-by: Alexey Dobriyan <[email protected]>
> ---
>
> fs/file.c | 5 -----
> fs/file_table.c | 10 ++++++++--
> include/linux/file.h | 2 --
> 3 files changed, 8 insertions(+), 9 deletions(-)
>
> --- a/fs/file.c
> +++ b/fs/file.c
> @@ -25,11 +25,6 @@
> #include "internal.h"
>
> unsigned int sysctl_nr_open __read_mostly = 1024*1024;
> -unsigned int sysctl_nr_open_min = BITS_PER_LONG;
> -/* our min() is unusable in constant expressions ;-/ */
> -#define __const_min(x, y) ((x) < (y) ? (x) : (y))
> -unsigned int sysctl_nr_open_max =
> - __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
>
> static void __free_fdtable(struct fdtable *fdt)
> {
> --- a/fs/file_table.c
> +++ b/fs/file_table.c
> @@ -111,6 +111,12 @@ static int proc_nr_files(struct ctl_table *table, int write, void *buffer,
> return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
> }
>
> +static const unsigned int sysctl_nr_open_min = BITS_PER_LONG;
> +/* our min() is unusable in constant expressions ;-/ */
> +#define __const_min(x, y) ((x) < (y) ? (x) : (y))
> +static const unsigned int sysctl_nr_open_max =
> + __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
I think you'll find that min() is fine.
Although those upper limits look suspect to me.
Looks like ~0.5G on 32bit and ~2G on 64bit based on the size of a bitmap?
But the kernel will run out of address space much earlier - esp on 32bit.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
On Thu, Oct 12, 2023 at 01:54:06PM +0000, David Laight wrote:
> From: Alexey Dobriyan
> > Sent: 11 October 2023 19:24
> > +/* our min() is unusable in constant expressions ;-/ */
> > +#define __const_min(x, y) ((x) < (y) ? (x) : (y))
> > +static const unsigned int sysctl_nr_open_max =
> > + __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
>
> I think you'll find that min() is fine.
Mainline min() still can't do
static const x = min(1, 2);
From: Alexey Dobriyan
> Sent: 14 October 2023 10:23
>
> On Thu, Oct 12, 2023 at 01:54:06PM +0000, David Laight wrote:
> > From: Alexey Dobriyan
> > > Sent: 11 October 2023 19:24
>
> > > +/* our min() is unusable in constant expressions ;-/ */
> > > +#define __const_min(x, y) ((x) < (y) ? (x) : (y))
> > > +static const unsigned int sysctl_nr_open_max =
> > > + __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
> >
> > I think you'll find that min() is fine.
>
> Mainline min() still can't do
>
> static const x = min(1, 2);
There has been a whole load of stuff that is supposed to do that
for ages - my changes don't affect it.
I presume they work - because they make it horribly complicated.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
From: Alexey Dobriyan
> Sent: 14 October 2023 10:23
>
> On Thu, Oct 12, 2023 at 01:54:06PM +0000, David Laight wrote:
> > From: Alexey Dobriyan
> > > Sent: 11 October 2023 19:24
>
> > > +/* our min() is unusable in constant expressions ;-/ */
> > > +#define __const_min(x, y) ((x) < (y) ? (x) : (y))
> > > +static const unsigned int sysctl_nr_open_max =
> > > + __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;
> >
> > I think you'll find that min() is fine.
>
> Mainline min() still can't do
>
> static const x = min(1, 2);
(second reply having realised what actually fails.)
That is ok.
The code actually falls foul of the type check.
The LHS will be 'signed int' and the RHS 'size_t' which IIRC is
'unsigned int' on 32 bit and 'unsigned long' on 64 bit.
So the comment is explaining the wrong error.
Changing to (size_t)INT_MAX should make min() work.
My new version should let that through, it allows unsigned
against non-negative signed constants.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)