On Sun, Aug 06, 2006 at 05:44:31PM +0200, Paolo 'Blaisorblade' Giarrusso wrote:
> I had this patch in my queue since some time, because it fixes some spinlocks
> vs
> sleeps issues; please verify whether after your restructuring it is still
> needed (it applied before this restructuring).
I believe this patch is no longer needed. It looks like all calls to
activate_fd are in process context. However, there are a few places
where it can be reached inside a spinlock. These cases look like the
spinlock is held for too long, and needs to be narrowed.
Here's my work, if you feel like checking it. Increasing indendation
is going up the call chain. At the top of each chain, there's a
"proc", along with my reason for believing the procedure is only
called in process context. When that's not there, it's because that
call tree had already been covered ealier.
There's some stuff in the network which I didn't go into because it's
code I have no clue about.
Every procedure can call activate_fd under a spinlock is so marked.
activate_fd can recurse to itself, but only once. This happens when
the first descriptor needing sigio coverage is activated. The sigio
thread will be started, a pipe to it created, and an irq registered
for that pipe.
activate_fd
um_request_irq
line_setup_irq
enable_chan
line_open - SPINLOCK
ssl_open, con_open - tty_operations.open
tty_open - proc, in response to open(2)
register_winch_irq
register_winch
chan_enable_winch
line_open
is_tracer_winch, is_skas_winch
register_winch
mconsole_fuse - proc, work_proc
mconsole_init - proc, initcall
uml_net_open - struct net_device.open, SPINLOCK
dev_open
dev_change_flags - ?
ipmr_new_tunnel - ?
ipmr_reg_vif - ?
port_accept
port_work_proc - proc, work_proc
port_data
port_init - chan_ops.init
parse_chan
parse_chan_pair
line_config
lines_init
ssl_config, con_config
line_driver.mc.config - mconsole_devices
mconsole_config - proc, work_proc
xterm_fd
xterm_open
chan_ops.open
open_one_chan
open_chan
console_open_chan
ssl_console_setup, uml_console_setup - struct
console.setup
register_console
mc_add_console - proc, initcall
ssl_init - proc, initcall
stderr_console_init - proc, initcall
stdio_init - proc, initcall
x11_probe
x11_init - proc, initcall
init_aio_irq
init_aio - proc, initcall
write_sigio_irq
write_sigio_workaround - SPINLOCK
maybe_sigio_broken
activate_fd
Jeff
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