[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: Mike Waychison <mikew@google.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/ipc/util.c b/ipc/util.c
index e00c35f..10e836d 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -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 @@
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 @@
}
#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 */