diff options
| -rw-r--r-- | fs/devpts/inode.c | 34 | ||||
| -rw-r--r-- | include/linux/tty.h | 1 |
2 files changed, 31 insertions, 4 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index c2c7317d568..1c6f908e38c 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 d3ebd765b54..d4077418820 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 */ /* |