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Commit ae781774 authored by Mike Waychison's avatar Mike Waychison Committed by Linus Torvalds
Browse files

[PATCH] ipc: add generic struct ipc_ids seq_file iteration 



The following two patches convert /proc/sysvipc/* to use seq_file.

This gives us the following:

 - Self-consistent IPC records in proc.
 - O(n) reading of the files themselves.

This patch:

Add a generic method for ipc types to be displayed using seq_file.  This
patch abstracts out seq_file iterating over struct ipc_ids into ipc/util.c

Signed-off-by: default avatarMike Waychison <mikew@google.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f35279d3

ipc/util.c

+156 −0
Original line number Diff line number Diff line
@@ -24,11 +24,20 @@ 
#include <linux/security.h>

#include <linux/rcupdate.h>

#include <linux/workqueue.h>

#include <linux/seq_file.h>

#include <linux/proc_fs.h>



#include <asm/unistd.h>



#include "util.h"



struct ipc_proc_iface {

	const char *path;

	const char *header;

	struct ipc_ids *ids;

	int (*show)(struct seq_file *, void *);

};



/**

 *	ipc_init	-	initialise IPC subsystem

 *
@@ -86,6 +95,43 @@ void __init ipc_init_ids(struct ipc_ids* ids, int size) 
		ids->entries->p[i] = NULL;

}



#ifdef CONFIG_PROC_FS

static struct file_operations sysvipc_proc_fops;

/**

 *	ipc_init_proc_interface	-  Create a proc interface for sysipc types

 *				   using a seq_file interface.

 *	@path: Path in procfs

 *	@header: Banner to be printed at the beginning of the file.

 *	@ids: ipc id table to iterate.

 *	@show: show routine.

 */

void __init ipc_init_proc_interface(const char *path, const char *header,

				    struct ipc_ids *ids,

				    int (*show)(struct seq_file *, void *))

{

	struct proc_dir_entry *pde;

	struct ipc_proc_iface *iface;



	iface = kmalloc(sizeof(*iface), GFP_KERNEL);

	if (!iface)

		return;

	iface->path	= path;

	iface->header	= header;

	iface->ids	= ids;

	iface->show	= show;



	pde = create_proc_entry(path,

				S_IRUGO,        /* world readable */

				NULL            /* parent dir */);

	if (pde) {

		pde->data = iface;

		pde->proc_fops = &sysvipc_proc_fops;

	} else {

		kfree(iface);

	}

}

#endif



/**

 *	ipc_findkey	-	find a key in an ipc identifier set	

 *	@ids: Identifier set
@@ -578,3 +624,113 @@ int ipc_parse_version (int *cmd) 
}



#endif /* __ARCH_WANT_IPC_PARSE_VERSION */



#ifdef CONFIG_PROC_FS

static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)

{

	struct ipc_proc_iface *iface = s->private;

	struct kern_ipc_perm *ipc = it;

	loff_t p;



	/* If we had an ipc id locked before, unlock it */

	if (ipc && ipc != SEQ_START_TOKEN)

		ipc_unlock(ipc);



	/*

	 * p = *pos - 1 (because id 0 starts at position 1)

	 *          + 1 (because we increment the position by one)

	 */

	for (p = *pos; p <= iface->ids->max_id; p++) {

		if ((ipc = ipc_lock(iface->ids, p)) != NULL) {

			*pos = p + 1;

			return ipc;

		}

	}



	/* Out of range - return NULL to terminate iteration */

	return NULL;

}



/*

 * File positions: pos 0 -> header, pos n -> ipc id + 1.

 * SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.

 */

static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)

{

	struct ipc_proc_iface *iface = s->private;

	struct kern_ipc_perm *ipc;

	loff_t p;



	/*

	 * Take the lock - this will be released by the corresponding

	 * call to stop().

	 */

	down(&iface->ids->sem);



	/* pos < 0 is invalid */

	if (*pos < 0)

		return NULL;



	/* pos == 0 means header */

	if (*pos == 0)

		return SEQ_START_TOKEN;



	/* Find the (pos-1)th ipc */

	for (p = *pos - 1; p <= iface->ids->max_id; p++) {

		if ((ipc = ipc_lock(iface->ids, p)) != NULL) {

			*pos = p + 1;

			return ipc;

		}

	}

	return NULL;

}



static void sysvipc_proc_stop(struct seq_file *s, void *it)

{

	struct kern_ipc_perm *ipc = it;

	struct ipc_proc_iface *iface = s->private;



	/* If we had a locked segment, release it */

	if (ipc && ipc != SEQ_START_TOKEN)

		ipc_unlock(ipc);



	/* Release the lock we took in start() */

	up(&iface->ids->sem);

}



static int sysvipc_proc_show(struct seq_file *s, void *it)

{

	struct ipc_proc_iface *iface = s->private;



	if (it == SEQ_START_TOKEN)

		return seq_puts(s, iface->header);



	return iface->show(s, it);

}



static struct seq_operations sysvipc_proc_seqops = {

	.start = sysvipc_proc_start,

	.stop  = sysvipc_proc_stop,

	.next  = sysvipc_proc_next,

	.show  = sysvipc_proc_show,

};



static int sysvipc_proc_open(struct inode *inode, struct file *file) {

	int ret;

	struct seq_file *seq;



	ret = seq_open(file, &sysvipc_proc_seqops);

	if (!ret) {

		seq = file->private_data;

		seq->private = PDE(inode)->data;

	}

	return ret;

}



static struct file_operations sysvipc_proc_fops = {

	.open    = sysvipc_proc_open,

	.read    = seq_read,

	.llseek  = seq_lseek,

	.release = seq_release,

};

#endif /* CONFIG_PROC_FS */

ipc/util.h

+8 −0
Original line number Diff line number Diff line
@@ -30,7 +30,15 @@ struct ipc_ids { 
	struct ipc_id_ary* entries;

};



struct seq_file;

void __init ipc_init_ids(struct ipc_ids* ids, int size);

#ifdef CONFIG_PROC_FS

void __init ipc_init_proc_interface(const char *path, const char *header,

				    struct ipc_ids *ids,

				    int (*show)(struct seq_file *, void *));

#else

#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)

#endif



/* must be called with ids->sem acquired.*/

int ipc_findkey(struct ipc_ids* ids, key_t key);