qemu/scripts/block-coroutine-wrapper.py
Kevin Wolf d6ee2e324e block-coroutine-wrapper: Introduce no_co_wrapper
Some functions must not be called from coroutine context. The common
pattern to use them anyway from a coroutine is running them in a BH and
letting the calling coroutine yield to be woken up when the BH is
completed.

Instead of manually writing such wrappers, add support for generating
them to block-coroutine-wrapper.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230126172432.436111-2-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-02-17 11:22:19 +01:00

308 lines
8.8 KiB
Python

#! /usr/bin/env python3
"""Generate coroutine wrappers for block subsystem.
The program parses one or several concatenated c files from stdin,
searches for functions with the 'co_wrapper' specifier
and generates corresponding wrappers on stdout.
Usage: block-coroutine-wrapper.py generated-file.c FILE.[ch]...
Copyright (c) 2020 Virtuozzo International GmbH.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import sys
import re
from typing import Iterator
def gen_header():
copyright = re.sub('^.*Copyright', 'Copyright', __doc__, flags=re.DOTALL)
copyright = re.sub('^(?=.)', ' * ', copyright.strip(), flags=re.MULTILINE)
copyright = re.sub('^$', ' *', copyright, flags=re.MULTILINE)
return f"""\
/*
* File is generated by scripts/block-coroutine-wrapper.py
*
{copyright}
*/
#include "qemu/osdep.h"
#include "block/coroutines.h"
#include "block/block-gen.h"
#include "block/block_int.h"
#include "block/dirty-bitmap.h"
"""
class ParamDecl:
param_re = re.compile(r'(?P<decl>'
r'(?P<type>.*[ *])'
r'(?P<name>[a-z][a-z0-9_]*)'
r')')
def __init__(self, param_decl: str) -> None:
m = self.param_re.match(param_decl.strip())
if m is None:
raise ValueError(f'Wrong parameter declaration: "{param_decl}"')
self.decl = m.group('decl')
self.type = m.group('type')
self.name = m.group('name')
class FuncDecl:
def __init__(self, wrapper_type: str, return_type: str, name: str,
args: str, variant: str) -> None:
self.return_type = return_type.strip()
self.name = name.strip()
self.struct_name = snake_to_camel(self.name)
self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
self.create_only_co = 'mixed' not in variant
self.graph_rdlock = 'bdrv_rdlock' in variant
self.wrapper_type = wrapper_type
if wrapper_type == 'co':
subsystem, subname = self.name.split('_', 1)
self.target_name = f'{subsystem}_co_{subname}'
else:
assert wrapper_type == 'no_co'
subsystem, co_infix, subname = self.name.split('_', 2)
if co_infix != 'co':
raise ValueError(f"Invalid no_co function name: {self.name}")
if not self.create_only_co:
raise ValueError(f"no_co function can't be mixed: {self.name}")
if self.graph_rdlock:
raise ValueError(f"no_co function can't be rdlock: {self.name}")
self.target_name = f'{subsystem}_{subname}'
t = self.args[0].type
if t == 'BlockDriverState *':
ctx = 'bdrv_get_aio_context(bs)'
elif t == 'BdrvChild *':
ctx = 'bdrv_get_aio_context(child->bs)'
elif t == 'BlockBackend *':
ctx = 'blk_get_aio_context(blk)'
else:
ctx = 'qemu_get_aio_context()'
self.ctx = ctx
self.get_result = 's->ret = '
self.ret = 'return s.ret;'
self.co_ret = 'return '
self.return_field = self.return_type + " ret;"
if self.return_type == 'void':
self.get_result = ''
self.ret = ''
self.co_ret = ''
self.return_field = ''
def gen_list(self, format: str) -> str:
return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
def gen_block(self, format: str) -> str:
return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
# Match wrappers declared with a co_wrapper mark
func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
r'(\s*coroutine_fn)?'
r'\s*(?P<wrapper_type>(no_)?co)_wrapper'
r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
r'\((?P<args>[^)]*)\);$', re.MULTILINE)
def func_decl_iter(text: str) -> Iterator:
for m in func_decl_re.finditer(text):
yield FuncDecl(wrapper_type=m.group('wrapper_type'),
return_type=m.group('return_type'),
name=m.group('wrapper_name'),
args=m.group('args'),
variant=m.group('variant'))
def snake_to_camel(func_name: str) -> str:
"""
Convert underscore names like 'some_function_name' to camel-case like
'SomeFunctionName'
"""
words = func_name.split('_')
words = [w[0].upper() + w[1:] for w in words]
return ''.join(words)
def create_mixed_wrapper(func: FuncDecl) -> str:
"""
Checks if we are already in coroutine
"""
name = func.target_name
struct_name = func.struct_name
graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
return f"""\
{func.return_type} {func.name}({ func.gen_list('{decl}') })
{{
if (qemu_in_coroutine()) {{
{graph_assume_lock}
{func.co_ret}{name}({ func.gen_list('{name}') });
}} else {{
{struct_name} s = {{
.poll_state.ctx = {func.ctx},
.poll_state.in_progress = true,
{ func.gen_block(' .{name} = {name},') }
}};
s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
bdrv_poll_co(&s.poll_state);
{func.ret}
}}
}}"""
def create_co_wrapper(func: FuncDecl) -> str:
"""
Assumes we are not in coroutine, and creates one
"""
name = func.target_name
struct_name = func.struct_name
return f"""\
{func.return_type} {func.name}({ func.gen_list('{decl}') })
{{
{struct_name} s = {{
.poll_state.ctx = {func.ctx},
.poll_state.in_progress = true,
{ func.gen_block(' .{name} = {name},') }
}};
assert(!qemu_in_coroutine());
s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
bdrv_poll_co(&s.poll_state);
{func.ret}
}}"""
def gen_co_wrapper(func: FuncDecl) -> str:
assert not '_co_' in func.name
assert func.wrapper_type == 'co'
name = func.target_name
struct_name = func.struct_name
graph_lock=''
graph_unlock=''
if func.graph_rdlock:
graph_lock=' bdrv_graph_co_rdlock();'
graph_unlock=' bdrv_graph_co_rdunlock();'
creation_function = create_mixed_wrapper
if func.create_only_co:
creation_function = create_co_wrapper
return f"""\
/*
* Wrappers for {name}
*/
typedef struct {struct_name} {{
BdrvPollCo poll_state;
{func.return_field}
{ func.gen_block(' {decl};') }
}} {struct_name};
static void coroutine_fn {name}_entry(void *opaque)
{{
{struct_name} *s = opaque;
{graph_lock}
{func.get_result}{name}({ func.gen_list('s->{name}') });
{graph_unlock}
s->poll_state.in_progress = false;
aio_wait_kick();
}}
{creation_function(func)}"""
def gen_no_co_wrapper(func: FuncDecl) -> str:
assert '_co_' in func.name
assert func.wrapper_type == 'no_co'
name = func.target_name
struct_name = func.struct_name
return f"""\
/*
* Wrappers for {name}
*/
typedef struct {struct_name} {{
Coroutine *co;
{func.return_field}
{ func.gen_block(' {decl};') }
}} {struct_name};
static void {name}_bh(void *opaque)
{{
{struct_name} *s = opaque;
{func.get_result}{name}({ func.gen_list('s->{name}') });
aio_co_wake(s->co);
}}
{func.return_type} coroutine_fn {func.name}({ func.gen_list('{decl}') })
{{
{struct_name} s = {{
.co = qemu_coroutine_self(),
{ func.gen_block(' .{name} = {name},') }
}};
assert(qemu_in_coroutine());
aio_bh_schedule_oneshot(qemu_get_aio_context(), {name}_bh, &s);
qemu_coroutine_yield();
{func.ret}
}}"""
def gen_wrappers(input_code: str) -> str:
res = ''
for func in func_decl_iter(input_code):
res += '\n\n\n'
if func.wrapper_type == 'co':
res += gen_co_wrapper(func)
else:
res += gen_no_co_wrapper(func)
return res
if __name__ == '__main__':
if len(sys.argv) < 3:
exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
f_out.write(gen_header())
for fname in sys.argv[2:]:
with open(fname, encoding='utf-8') as f_in:
f_out.write(gen_wrappers(f_in.read()))
f_out.write('\n')