Commits
Ivo Sieben committed 98001214c04
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 <meltedpianoman@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>