From 98001214c0436c2b697d696fde3696d32620d394 Mon Sep 17 00:00:00 2001 From: Ivo Sieben Date: Mon, 28 Jan 2013 13:32:01 +0100 Subject: [PATCH] tty: Use raw spin lock to protect the TTY read section The "normal" spin lock that guards the N_TTY line discipline read section is replaced by a raw spin lock. On a PREEMP_RT system this prevents unwanted scheduling overhead when data is read at the same time as data is being received: while RX IRQ threaded handling is busy a TTY read call is performed from a RT priority > threaded IRQ priority. The read call tries to take the read section spin lock (held by the threaded IRQ) which blocks and causes a context switch to/from the threaded IRQ handler until the spin lock is unlocked. Signed-off-by: Ivo Sieben Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- Reading git-format-patch failed