The SoC serial port driver uses a high priority interrupt to handle tx of
characters in the tx ring buffer. The driver needs to disable/enable this IRQ
from outside of irq context. The original code to do this is not foolproof on
SMP machines because the IRQ running on one core could still access the serial
port for a short time after the driver running on another core disables the
interrupt. This patch adds a flag to tell the IRQ handler that the driver
wants to disable the interrupt. After seeing the flag, the IRQ handler will
immediately disable the interrupt and exit. After setting the flag, the driver
will wait for interrupt to be disabled by the IRQ handler.
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
The builtin SoC serial ports have no FIFOs and use a virtual DMA mechanism
based on high priority IRQs to avoid overruns. These high priority interrupts
are pinned to cpu#0 on SMP systems. This patch fixes a problem with SMP where
the set_intr_level() interface is used to set the priority for these IRQs. The
set_intr_level() function sets priority on the local cpu but on SMP systems,
this code may be run on some other cpu than the one handling the interrupts.
Instead of setting interrupt level explicitly, this patch uses a special
irq_chip for these interrupts so that the mask/unmask methods can set the
interrupt level implicitly.
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
The irq_set_affinity handler for the mn10300 cpu pic had some hard-coded IRQs
which were not to be migrated from one cpu to another. This patch cleans those
up by using a combination of IRQF_NOBALANCING and specialized irq chips with
no irq_set_affinity handler. This maintains the previous behavior by using
generic IRQ interfaces rather than hard coding IRQ numbers in the default
irq_set_affinity handler.
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Use memory barriers correctly in the circular buffer logic used in the driver,
as documented in Documentation/circular-buffers.txt.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
the first one is equal to signal_pt_regs(), the second is never used
(and always NULL, while we are at it).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Always equal to task_pt_regs(current); defined only when we are in
signal delivery. It may be different from current_pt_regs() - e.g.
architectures like m68k may have pt_regs location on exception
different from that on a syscall and signals (just as ptrace handling)
may happen on exceptions as well as on syscalls.
When they are equal, it's often better to have signal_pt_regs
defined (in asm/ptrace.h) as current_pt_regs - that tends to be
optimized better than default would be. However, optimisation is
the only reason why we might want an arch-specific definition;
if current_pt_regs() and task_pt_regs(current) have different
values, the latter one is right.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and get rid of idiotic struct pt_regs * in asm-generic/syscalls.h
prototypes of the same, while we are at it. Eventually we want those
in linux/syscalls.h, of course, but that'll have to wait a bit.
Note that there are *three* variants of sys_clone() order of arguments.
Braindamage galore...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Mark Salter