lib: drop ff_kernel_coexist_enabled accessor, read ff_global_cfg directly

The accessor only wrapped a single struct member read and required two
identical declarations (ff_config.h + ff_host_interface.h) because the
host-bridge header intentionally avoids depending on ff_config.h.

Remove the accessor entirely; the sole caller (ff_syscall_wrapper.c)
now includes ff_config.h and reads ff_global_cfg.stack.kernel_coexist
directly. ff_host_interface.h keeps its lightweight host-bridge scope
(no ff_config.h pull-in). Unit tests drop the redundant accessor
assertions but still assert the underlying global. Spec docs updated
to match the implementation.

Author: jfb8856606

docs/kernel_event_support_spec/06-milestones.md

@@ -37,7 +37,7 @@
 
 ## 3. R3 Native ff_api Unified-Event Coexistence (new design, core change)
 **Coding work list**:
-1. `lib/ff_config.{c,h}`: change the v3 `stack.default_to_kernel`/`default_stack` to `stack.kernel_coexist` (`MATCH("stack","kernel_coexist")`, default 0); sync the `test_ff_config` cases and fixtures, the `config.ini` example section, and the accessor (e.g., `ff_kernel_coexist_enabled()`).
+1. `lib/ff_config.{c,h}`: change the v3 `stack.default_to_kernel`/`default_stack` to `stack.kernel_coexist` (`MATCH("stack","kernel_coexist")`, default 0); sync the `test_ff_config` cases and fixtures, the `config.ini` example section; callers read `ff_global_cfg.stack.kernel_coexist` directly (no accessor).
 2. `lib/ff_host_interface.{c,h}`: add a **managed kernel-side bridge** (host `socket/bind/listen/accept/connect/close/epoll_create1/epoll_ctl/epoll_wait`) for lib to create managed kernel fds (**not a raw bypass**; lib registers ownership).
 3. lib-internal fd-ownership mechanism: an ownership table / encoded offset distinguishes managed kernel fds from F-Stack fds; `ff_socket(SOCK_KERNEL)` (when coexistence enabled) creates a managed kernel fd and registers it; default/`SOCK_FSTACK` go the original `sys_socket` (byte-for-byte zero regression).
 4. `ff_bind/ff_listen/ff_accept/ff_connect/ff_close`: route by ownership at the entry (kernel fd → managed host bridge; F-Stack fd → original path).

docs/kernel_event_support_spec/08-review-gate.md

@@ -40,7 +40,7 @@
 ### I.1 Code-Change Verification (all PASS)
 | ID | Assertion | Result | Evidence |
 |---|---|---|---|
-| I1 | config coexistence switch (R3.1) | PASS | `ff_config.h` `struct{int kernel_coexist;}stack;`; `ff_config.c` `MATCH("stack","kernel_coexist")`(1/on/true/yes→1), default 0, `ff_kernel_coexist_enabled()` |
+| I1 | config coexistence switch (R3.1) | PASS | `ff_config.h` `struct{int kernel_coexist;}stack;`; `ff_config.c` `MATCH("stack","kernel_coexist")`(1/on/true/yes→1), default 0; callers read `ff_global_cfg.stack.kernel_coexist` directly |
 | I2 | FD-space scheme (no collision) | PASS | `ff_host_interface.h` `FF_KERNEL_FD_BASE 0x40000000`, `ff_is_kernel_fd/encode/real` (above FreeBSD fd ≤65536, host fds bounded by RLIMIT) |
 | I3 | host bridge (managed kernel fd, not a raw bypass) | PASS | `ff_host_interface.c` `ff_host_socket/bind/listen/accept/accept4/connect/close/read/write/recv/send/sendto/recvfrom/setsockopt/getsockopt/fcntl/epoll_create1/ctl/wait`; `_GNU_SOURCE` for accept4/epoll_create1 |
 | I4 | socket-side ownership routing (R3.2/3.3) | PASS | `ff_syscall_wrapper.c` `ff_socket`(SOCK_KERNEL+coexist→managed kernel fd) and close/read/write/sendto/recvfrom/accept/accept4/listen/bind/connect/setsockopt/getsockopt/fcntl entries route by `ff_is_kernel_fd` |

docs/kernel_event_support_spec/zh_cn/06-milestones.md

@@ -38,7 +38,7 @@
 
 ## 3. R3 原生 ff_api 统一事件共存（新设计，核心改造）
 **编码工作清单**：
-1. `lib/ff_config.{c,h}`：将 v3 `stack.default_to_kernel`/`default_stack` 改为 `stack.kernel_coexist`（`MATCH("stack","kernel_coexist")`，默认 0）；同步更新 `test_ff_config` 用例与 fixtures、`config.ini` 示例段、访问器（如 `ff_kernel_coexist_enabled()`）。
+1. `lib/ff_config.{c,h}`：将 v3 `stack.default_to_kernel`/`default_stack` 改为 `stack.kernel_coexist`（`MATCH("stack","kernel_coexist")`，默认 0）；同步更新 `test_ff_config` 用例与 fixtures、`config.ini` 示例段；调用方直接读 `ff_global_cfg.stack.kernel_coexist`，不引入访问器。
 2. `lib/ff_host_interface.{c,h}`：新增**受管内核侧桥**（宿主 `socket/bind/listen/accept/connect/close/epoll_create1/epoll_ctl/epoll_wait`），供 lib 调用建受管内核 fd（**非裸绕过**，由 lib 登记归属）。
 3. lib 内 fd 归属机制：归属表/编码偏移区分受管内核 fd 与 F-Stack fd；`ff_socket(SOCK_KERNEL)`（启用共存时）建受管内核 fd 并登记；默认/`SOCK_FSTACK` 走原 `sys_socket`（逐字节零回归）。
 4. `ff_bind/ff_listen/ff_accept/ff_connect/ff_close`：入口按归属路由（内核 fd → 受管宿主桥；F-Stack fd → 原路径）。

docs/kernel_event_support_spec/zh_cn/08-review-gate.md

@@ -43,7 +43,7 @@
 ### I.1 代码改动核验（全部 PASS）
 | 编号 | 断言 | 结果 | 证据 |
 |---|---|---|---|
-| I1 | config 共存开关（R3.1） | PASS | `ff_config.h` `struct{int kernel_coexist;}stack;`；`ff_config.c` `MATCH("stack","kernel_coexist")`(1/on/true/yes→1)、默认 0、`ff_kernel_coexist_enabled()` |
+| I1 | config 共存开关（R3.1） | PASS | `ff_config.h` `struct{int kernel_coexist;}stack;`；`ff_config.c` `MATCH("stack","kernel_coexist")`(1/on/true/yes→1)、默认 0；调用方直接读 `ff_global_cfg.stack.kernel_coexist` |
 | I2 | FD 空间方案（零冲突） | PASS | `ff_host_interface.h` `FF_KERNEL_FD_BASE 0x40000000`、`ff_is_kernel_fd/encode/real`（远超 FreeBSD fd≤65536，宿主 fd 受 RLIMIT 限） |
 | I3 | 宿主桥（受管内核 fd，非裸绕过） | PASS | `ff_host_interface.c` `ff_host_socket/bind/listen/accept/accept4/connect/close/read/write/recv/send/sendto/recvfrom/setsockopt/getsockopt/fcntl/epoll_create1/ctl/wait`；`_GNU_SOURCE` for accept4/epoll_create1 |
 | I4 | socket 侧归属路由（R3.2/3.3） | PASS | `ff_syscall_wrapper.c` `ff_socket`(SOCK_KERNEL+coexist→受管内核 fd) 及 close/read/write/sendto/recvfrom/accept/accept4/listen/bind/connect/setsockopt/getsockopt/fcntl 入口 `ff_is_kernel_fd` 路由 |

lib/ff_config.c

@@ -1376,12 +1376,6 @@ ff_default_config(struct ff_config *cfg)
     cfg->log.dir = strdup(FF_LOG_FILENAME_PREFIX);
 }
 
-int
-ff_kernel_coexist_enabled(void)
-{
-    return ff_global_cfg.stack.kernel_coexist;
-}
-
 int
 ff_load_config(int argc, char *const argv[])
 {

lib/ff_config.h

@@ -350,10 +350,6 @@ extern struct ff_config ff_global_cfg;
 
 int ff_load_config(int argc, char * const argv[]);
 
-/* Returns non-zero when kernel-stack coexistence is enabled for this process
- * (config.ini [stack] kernel_coexist=1). */
-int ff_kernel_coexist_enabled(void);
-
 void ff_unload_config(void);
 
 #ifdef __cplusplus

lib/ff_host_interface.h

@@ -126,9 +126,6 @@ static inline int ff_kernel_fd_real(int fd)
     return fd - FF_KERNEL_FD_BASE;
 }
 
-/* Defined in ff_config.c: non-zero when [stack] kernel_coexist=1. */
-int ff_kernel_coexist_enabled(void);
-
 /*
  * Host kernel-stack bridge (implemented in ff_host_interface.c, host
  * namespace). These operate on RAW host fds. sockaddr / epoll_event are

lib/ff_syscall_wrapper.c

@@ -61,6 +61,7 @@
 
 #include "ff_api.h"
 #include "ff_host_interface.h"
+#include "ff_config.h"
 
 /* setsockopt/getsockopt define start */
 
@@ -923,7 +924,7 @@ ff_socket(int domain, int type, int protocol)
      * byte-for-byte unchanged (NFR-1 zero regression).
      */
     if ((type & SOCK_KERNEL) && !(type & SOCK_FSTACK) &&
-        ff_kernel_coexist_enabled()) {
+        ff_global_cfg.stack.kernel_coexist) {
         int kfd = ff_host_socket(domain,
             type & ~(SOCK_KERNEL | SOCK_FSTACK), protocol);
         return kfd < 0 ? -1 : ff_kernel_fd_encode(kfd);

tests/unit/test_ff_config.c

@@ -1007,28 +1007,24 @@ test_bond_cfgs_calloc_oom_returns_error(void **state)
 /* ------------------------------------------------------------------------ */
 /* kernel_event_support (coexistence): [stack] kernel_coexist parsing        */
 /* ------------------------------------------------------------------------ */
-extern int ff_kernel_coexist_enabled(void);
-
-/* kernel_coexist=1 -> stack.kernel_coexist == 1 + accessor agrees */
+/* kernel_coexist=1 -> stack.kernel_coexist == 1 */
 static void
 test_ff_load_config_stack_coexist_enabled(void **state)
 {
     (void)state;
     int rv = load_with_fixture(FIXTURE_PATH("valid_stack_kernel.ini"));
     (void)rv;
     assert_int_equal(ff_global_cfg.stack.kernel_coexist, 1);
-    assert_int_equal(ff_kernel_coexist_enabled(), 1);
 }
 
-/* [stack] absent -> coexistence disabled (0); accessor returns 0 */
+/* [stack] absent -> coexistence disabled (0) */
 static void
 test_ff_load_config_stack_absent_defaults_disabled(void **state)
 {
     (void)state;
     int rv = load_with_fixture(FIXTURE_PATH("valid_minimal.ini"));
     (void)rv;
     assert_int_equal(ff_global_cfg.stack.kernel_coexist, 0);
-    assert_int_equal(ff_kernel_coexist_enabled(), 0);
 }
 
 /* kernel_coexist with an unrecognized value -> falls back to disabled (0) */
@@ -1039,7 +1035,6 @@ test_ff_load_config_stack_garbage_defaults_disabled(void **state)
     int rv = load_with_fixture(FIXTURE_PATH("valid_stack_garbage.ini"));
     (void)rv;
     assert_int_equal(ff_global_cfg.stack.kernel_coexist, 0);
-    assert_int_equal(ff_kernel_coexist_enabled(), 0);
 }
 
 /* explicit kernel_coexist=0 -> 0 (verified via valid_all_sections.ini) */