PTY: add kernel parameter to overwrite legacy pty count

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 11 insertions, 3 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a57c1f216b21..bdddd3cd46dd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1430,6 +1430,10 @@ and is between 256 and 4096 characters. It is defined in the file
         pt.             [PARIDE]
                         See Documentation/paride.txt.
 
+        pty.legacy_count=
+                        [KNL] Number of legacy pty's. Overwrites compiled-in
+                        default number.
+
         quiet           [KNL] Disable most log messages
 
         r128=           [HW,DRM]
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index de14aea34e11..73de77105fea 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -248,14 +248,19 @@ static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
         return -ENOIOCTLCMD;
 }
 
+static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
+module_param(legacy_count, int, 0);
+
 static void __init legacy_pty_init(void)
 {
+        if (legacy_count <= 0)
+                return;
 
-        pty_driver = alloc_tty_driver(NR_PTYS);
+        pty_driver = alloc_tty_driver(legacy_count);
         if (!pty_driver)
                 panic("Couldn't allocate pty driver");
 
-        pty_slave_driver = alloc_tty_driver(NR_PTYS);
+        pty_slave_driver = alloc_tty_driver(legacy_count);
         if (!pty_slave_driver)
                 panic("Couldn't allocate pty slave driver");
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 6570719eafdf..60478f6e5dc6 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -21,7 +21,6 @@
  * (Note: the *_driver.minor_start values 1, 64, 128, 192 are
  * hardcoded at present.)
  */
-#define NR_PTYS CONFIG_LEGACY_PTY_COUNT   /* Number of legacy ptys */
 #define NR_UNIX98_PTY_DEFAULT   4096      /* Default maximum for Unix98 ptys */
 #define NR_UNIX98_PTY_MAX       (1 << MINORBITS) /* Absolute limit */
 #define NR_LDISCS               17