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-rw-r--r--fs/devpts/inode.c34
-rw-r--r--include/linux/tty.h1
2 files changed, 31 insertions, 4 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index c2c7317..1c6f908 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -41,8 +41,9 @@
* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
*/
static int pty_limit = NR_UNIX98_PTY_DEFAULT;
+static int pty_reserve = NR_UNIX98_PTY_RESERVE;
static int pty_limit_min;
-static int pty_limit_max = NR_UNIX98_PTY_MAX;
+static int pty_limit_max = INT_MAX;
static int pty_count;
static struct ctl_table pty_table[] = {
@@ -55,6 +56,14 @@ static struct ctl_table pty_table[] = {
.extra1 = &pty_limit_min,
.extra2 = &pty_limit_max,
}, {
+ .procname = "reserve",
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .data = &pty_reserve,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &pty_limit_min,
+ .extra2 = &pty_limit_max,
+ }, {
.procname = "nr",
.maxlen = sizeof(int),
.mode = 0444,
@@ -94,10 +103,11 @@ struct pts_mount_opts {
umode_t mode;
umode_t ptmxmode;
int newinstance;
+ int max;
};
enum {
- Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance,
+ Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max,
Opt_err
};
@@ -108,6 +118,7 @@ static const match_table_t tokens = {
#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
{Opt_ptmxmode, "ptmxmode=%o"},
{Opt_newinstance, "newinstance"},
+ {Opt_max, "max=%d"},
#endif
{Opt_err, NULL}
};
@@ -154,6 +165,7 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
opts->gid = 0;
opts->mode = DEVPTS_DEFAULT_MODE;
opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
+ opts->max = NR_UNIX98_PTY_MAX;
/* newinstance makes sense only on initial mount */
if (op == PARSE_MOUNT)
@@ -197,6 +209,12 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
if (op == PARSE_MOUNT)
opts->newinstance = 1;
break;
+ case Opt_max:
+ if (match_int(&args[0], &option) ||
+ option < 0 || option > NR_UNIX98_PTY_MAX)
+ return -EINVAL;
+ opts->max = option;
+ break;
#endif
default:
printk(KERN_ERR "devpts: called with bogus options\n");
@@ -303,6 +321,8 @@ static int devpts_show_options(struct seq_file *seq, struct dentry *root)
seq_printf(seq, ",mode=%03o", opts->mode);
#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
+ if (opts->max < NR_UNIX98_PTY_MAX)
+ seq_printf(seq, ",max=%d", opts->max);
#endif
return 0;
@@ -483,6 +503,12 @@ retry:
return -ENOMEM;
mutex_lock(&allocated_ptys_lock);
+ if (pty_count >= pty_limit -
+ (fsi->mount_opts.newinstance ? pty_reserve : 0)) {
+ mutex_unlock(&allocated_ptys_lock);
+ return -ENOSPC;
+ }
+
ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
if (ida_ret < 0) {
mutex_unlock(&allocated_ptys_lock);
@@ -491,10 +517,10 @@ retry:
return -EIO;
}
- if (index >= pty_limit) {
+ if (index >= fsi->mount_opts.max) {
ida_remove(&fsi->allocated_ptys, index);
mutex_unlock(&allocated_ptys_lock);
- return -EIO;
+ return -ENOSPC;
}
pty_count++;
mutex_unlock(&allocated_ptys_lock);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index d3ebd76..d407741 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -52,6 +52,7 @@
* hardcoded at present.)
*/
#define NR_UNIX98_PTY_DEFAULT 4096 /* Default maximum for Unix98 ptys */
+#define NR_UNIX98_PTY_RESERVE 1024 /* Default reserve for main devpts */
#define NR_UNIX98_PTY_MAX (1 << MINORBITS) /* Absolute limit */
/*
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