Revision 8339f0008c47cdd921c73f6d53d5588b5484f93c authored by Eric W. Biederman on 29 January 2007, 20:19:05 UTC, committed by Linus Torvalds on 30 January 2007, 16:29:58 UTC
When the world was a simple and static place setting up irqs was easy.
It sufficed to allocate a linux irq number and a find a free cpu
vector we could receive that linux irq on.  In those days it was
a safe assumption that any allocated vector was actually in use
so after one global pass through all of the vectors we would have
none left.

These days things are much more dynamic with interrupt controllers
(in the form of MSI or MSI-X) appearing on plug in cards and linux
irqs appearing and disappearing.  As these irqs come and go vectors
are allocated and freed,  invalidating the ancient assumption that all
allocated vectors stayed in use forever.

So this patch modifies the vector allocator to walk through every
possible vector before giving up, and to check to see if a vector
is in use before assigning it.  With these changes we stop leaking
freed vectors and it becomes possible to allocate and free irq vectors
all day long.

This changed was modeled after the vector allocator on x86_64 where
this limitation has already been removed.  In essence we don't update
the static variables that hold the position of the last vector we
allocated until have successfully allocated another vector.  This
allows us to detect if we have completed one complete scan through
all of the possible vectors.

Acked-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Raw File
shmbuf.h
#ifndef _ASM_IA64_SHMBUF_H
#define _ASM_IA64_SHMBUF_H

/*
 * The shmid64_ds structure for IA-64 architecture.
 * Note extra padding because this structure is passed back and forth
 * between kernel and user space.
 *
 * Pad space is left for:
 * - 2 miscellaneous 64-bit values
 */

struct shmid64_ds {
	struct ipc64_perm	shm_perm;	/* operation perms */
	size_t			shm_segsz;	/* size of segment (bytes) */
	__kernel_time_t		shm_atime;	/* last attach time */
	__kernel_time_t		shm_dtime;	/* last detach time */
	__kernel_time_t		shm_ctime;	/* last change time */
	__kernel_pid_t		shm_cpid;	/* pid of creator */
	__kernel_pid_t		shm_lpid;	/* pid of last operator */
	unsigned long		shm_nattch;	/* no. of current attaches */
	unsigned long		__unused1;
	unsigned long		__unused2;
};

struct shminfo64 {
	unsigned long	shmmax;
	unsigned long	shmmin;
	unsigned long	shmmni;
	unsigned long	shmseg;
	unsigned long	shmall;
	unsigned long	__unused1;
	unsigned long	__unused2;
	unsigned long	__unused3;
	unsigned long	__unused4;
};

#endif /* _ASM_IA64_SHMBUF_H */
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