mirror of https://gitlab.com/qemu-project/qemu
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>
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@ -54,6 +54,20 @@
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#define co_wrapper_bdrv_rdlock no_coroutine_fn
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#define co_wrapper_bdrv_rdlock no_coroutine_fn
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#define co_wrapper_mixed_bdrv_rdlock no_coroutine_fn coroutine_mixed_fn
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#define co_wrapper_mixed_bdrv_rdlock no_coroutine_fn coroutine_mixed_fn
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/*
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* no_co_wrapper: Function specifier used by block-coroutine-wrapper.py
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*
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* Function specifier which does nothing but mark functions to be generated by
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* scripts/block-coroutine-wrapper.py.
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*
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* A no_co_wrapper function declaration creates a coroutine_fn wrapper around
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* functions that must not be called in coroutine context. It achieves this by
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* scheduling a BH in the bottom half that runs the respective non-coroutine
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* function. The coroutine yields after scheduling the BH and is reentered when
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* the wrapped function returns.
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*/
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#define no_co_wrapper
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#include "block/blockjob.h"
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#include "block/blockjob.h"
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/* block.c */
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/* block.c */
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@ -63,8 +63,8 @@ class ParamDecl:
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class FuncDecl:
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class FuncDecl:
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def __init__(self, return_type: str, name: str, args: str,
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def __init__(self, wrapper_type: str, return_type: str, name: str,
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variant: str) -> None:
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args: str, variant: str) -> None:
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self.return_type = return_type.strip()
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self.return_type = return_type.strip()
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self.name = name.strip()
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self.name = name.strip()
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self.struct_name = snake_to_camel(self.name)
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self.struct_name = snake_to_camel(self.name)
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@ -72,8 +72,21 @@ class FuncDecl:
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self.create_only_co = 'mixed' not in variant
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self.create_only_co = 'mixed' not in variant
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self.graph_rdlock = 'bdrv_rdlock' in variant
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self.graph_rdlock = 'bdrv_rdlock' in variant
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subsystem, subname = self.name.split('_', 1)
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self.wrapper_type = wrapper_type
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self.co_name = f'{subsystem}_co_{subname}'
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if wrapper_type == 'co':
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subsystem, subname = self.name.split('_', 1)
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self.target_name = f'{subsystem}_co_{subname}'
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else:
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assert wrapper_type == 'no_co'
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subsystem, co_infix, subname = self.name.split('_', 2)
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if co_infix != 'co':
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raise ValueError(f"Invalid no_co function name: {self.name}")
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if not self.create_only_co:
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raise ValueError(f"no_co function can't be mixed: {self.name}")
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if self.graph_rdlock:
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raise ValueError(f"no_co function can't be rdlock: {self.name}")
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self.target_name = f'{subsystem}_{subname}'
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t = self.args[0].type
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t = self.args[0].type
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if t == 'BlockDriverState *':
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if t == 'BlockDriverState *':
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@ -105,7 +118,8 @@ class FuncDecl:
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# Match wrappers declared with a co_wrapper mark
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# Match wrappers declared with a co_wrapper mark
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func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
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func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
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r'\s*co_wrapper'
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r'(\s*coroutine_fn)?'
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r'\s*(?P<wrapper_type>(no_)?co)_wrapper'
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r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
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r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
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r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
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r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
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r'\((?P<args>[^)]*)\);$', re.MULTILINE)
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r'\((?P<args>[^)]*)\);$', re.MULTILINE)
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@ -113,7 +127,8 @@ func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
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def func_decl_iter(text: str) -> Iterator:
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def func_decl_iter(text: str) -> Iterator:
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for m in func_decl_re.finditer(text):
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for m in func_decl_re.finditer(text):
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yield FuncDecl(return_type=m.group('return_type'),
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yield FuncDecl(wrapper_type=m.group('wrapper_type'),
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return_type=m.group('return_type'),
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name=m.group('wrapper_name'),
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name=m.group('wrapper_name'),
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args=m.group('args'),
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args=m.group('args'),
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variant=m.group('variant'))
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variant=m.group('variant'))
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@ -133,7 +148,7 @@ def create_mixed_wrapper(func: FuncDecl) -> str:
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"""
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"""
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Checks if we are already in coroutine
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Checks if we are already in coroutine
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"""
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"""
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name = func.co_name
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name = func.target_name
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struct_name = func.struct_name
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struct_name = func.struct_name
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graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
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graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
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@ -163,7 +178,7 @@ def create_co_wrapper(func: FuncDecl) -> str:
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"""
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"""
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Assumes we are not in coroutine, and creates one
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Assumes we are not in coroutine, and creates one
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"""
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"""
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name = func.co_name
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name = func.target_name
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struct_name = func.struct_name
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struct_name = func.struct_name
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return f"""\
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return f"""\
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{func.return_type} {func.name}({ func.gen_list('{decl}') })
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{func.return_type} {func.name}({ func.gen_list('{decl}') })
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@ -183,10 +198,11 @@ def create_co_wrapper(func: FuncDecl) -> str:
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}}"""
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}}"""
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def gen_wrapper(func: FuncDecl) -> str:
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def gen_co_wrapper(func: FuncDecl) -> str:
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assert not '_co_' in func.name
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assert not '_co_' in func.name
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assert func.wrapper_type == 'co'
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name = func.co_name
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name = func.target_name
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struct_name = func.struct_name
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struct_name = func.struct_name
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graph_lock=''
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graph_lock=''
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@ -225,11 +241,56 @@ static void coroutine_fn {name}_entry(void *opaque)
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{creation_function(func)}"""
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{creation_function(func)}"""
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def gen_no_co_wrapper(func: FuncDecl) -> str:
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assert '_co_' in func.name
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assert func.wrapper_type == 'no_co'
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name = func.target_name
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struct_name = func.struct_name
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return f"""\
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/*
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* Wrappers for {name}
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*/
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typedef struct {struct_name} {{
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Coroutine *co;
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{func.return_field}
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{ func.gen_block(' {decl};') }
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}} {struct_name};
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static void {name}_bh(void *opaque)
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{{
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{struct_name} *s = opaque;
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{func.get_result}{name}({ func.gen_list('s->{name}') });
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aio_co_wake(s->co);
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}}
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{func.return_type} coroutine_fn {func.name}({ func.gen_list('{decl}') })
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{{
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{struct_name} s = {{
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.co = qemu_coroutine_self(),
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{ func.gen_block(' .{name} = {name},') }
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}};
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assert(qemu_in_coroutine());
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aio_bh_schedule_oneshot(qemu_get_aio_context(), {name}_bh, &s);
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qemu_coroutine_yield();
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{func.ret}
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}}"""
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def gen_wrappers(input_code: str) -> str:
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def gen_wrappers(input_code: str) -> str:
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res = ''
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res = ''
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for func in func_decl_iter(input_code):
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for func in func_decl_iter(input_code):
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res += '\n\n\n'
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res += '\n\n\n'
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res += gen_wrapper(func)
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if func.wrapper_type == 'co':
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res += gen_co_wrapper(func)
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else:
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res += gen_no_co_wrapper(func)
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return res
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return res
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