Messages in this thread | | | From | "Michael Kerrisk (man-pages)" <> | Date | Tue, 13 May 2014 08:06:21 +0200 | Subject | Re: [PATCH v2] ipc,shm: document new limits in the uapi header |
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On Tue, May 13, 2014 at 3:35 AM, Davidlohr Bueso <davidlohr@hp.com> wrote: > On Mon, 2014-05-12 at 09:44 +0200, Michael Kerrisk (man-pages) wrote: [...] >> The problem is that part of your text is still broken grammatically In >> particular, the piece "Both SHMMAX and SHMALL have their default >> values to the maximum limit" at the very least lacks a word. That's >> what prompted me to propose the alternative, rather than just say >> "this is wrong"--and I thought that I might as well make a more >> thoroughgoing attempt at helping improve the text. >> >> I agree that text something like this should land in the man page at >> some point, but as long as we're going to the trouble to improve the >> comments in the code, let's make them as good and helpful as we can. > > Fair enough, and I trust your grammar corrections over mine ;) Thanks > for taking a closer look. I've added your text below.
Thanks.
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cheers,'
Michael
> 8<------------------------------------------ > From: Davidlohr Bueso <davidlohr@hp.com> > Subject: [PATCH v3] ipc,shm: document new limits in the uapi header > > This is useful in the future and allows users to > better understand the reasoning behind the changes. > > Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> > --- > include/uapi/linux/shm.h | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h > index 74e786d..1fbf24e 100644 > --- a/include/uapi/linux/shm.h > +++ b/include/uapi/linux/shm.h > @@ -8,17 +8,20 @@ > #endif > > /* > - * SHMMAX, SHMMNI and SHMALL are upper limits are defaults which can > - * be modified by sysctl. > + * SHMMNI, SHMMAX and SHMALL are default upper limits which can be > + * modified by sysctl. The SHMMAX and SHMALL values have been chosen to > + * be as large possible without facilitating scenarios where userspace > + * causes overflows when adjusting the limits via operations of the form > + * "retrieve current limit; add X; update limit". It is therefore not > + * advised to make SHMMAX and SHMALL any larger. These limits are > + * suitable for both 32 and 64-bit systems. > */ > - > #define SHMMIN 1 /* min shared seg size (bytes) */ > #define SHMMNI 4096 /* max num of segs system wide */ > -#define SHMMAX (ULONG_MAX - (1L<<24)) /* max shared seg size (bytes) */ > -#define SHMALL (ULONG_MAX - (1L<<24)) /* max shm system wide (pages) */ > +#define SHMMAX (ULONG_MAX - (1UL << 24)) /* max shared seg size (bytes) */ > +#define SHMALL (ULONG_MAX - (1UL << 24)) /* max shm system wide (pages) */ > #define SHMSEG SHMMNI /* max shared segs per process */ > > - > /* Obsolete, used only for backwards compatibility and libc5 compiles */ > struct shmid_ds { > struct ipc_perm shm_perm; /* operation perms */ > -- > 1.8.1.4 > > > >
-- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
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