Change liveupdate_unregister_file_handler and liveupdate_unregister_flb
to return void instead of an error code. If they fail to unregister
due to dangling references, print a warning instead of aborting.
As pointed out by Jason Gunthorpe and Alex Williamson, returning an error
from a "destroy" or unregister function during a module unload is a poor
API choice since the unload cannot be stopped at that point.
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
include/linux/liveupdate.h | 13 ++++++------
kernel/liveupdate/luo_file.c | 27 +++++++++++-------------
kernel/liveupdate/luo_flb.c | 40 ++++++++++--------------------------
lib/tests/liveupdate.c | 8 ++------
4 files changed, 31 insertions(+), 57 deletions(-)
diff --git a/include/linux/liveupdate.h b/include/linux/liveupdate.h
index 8394fb2d8774..293df26b9e7f 100644
--- a/include/linux/liveupdate.h
+++ b/include/linux/liveupdate.h
@@ -231,12 +231,12 @@ bool liveupdate_enabled(void);
int liveupdate_reboot(void);
int liveupdate_register_file_handler(struct liveupdate_file_handler *fh);
-int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh);
+void liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh);
int liveupdate_register_flb(struct liveupdate_file_handler *fh,
struct liveupdate_flb *flb);
-int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
- struct liveupdate_flb *flb);
+void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
+ struct liveupdate_flb *flb);
int liveupdate_flb_get_incoming(struct liveupdate_flb *flb, void **objp);
int liveupdate_flb_get_outgoing(struct liveupdate_flb *flb, void **objp);
@@ -258,9 +258,8 @@ static inline int liveupdate_register_file_handler(struct liveupdate_file_handle
return -EOPNOTSUPP;
}
-static inline int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
+static inline void liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
{
- return -EOPNOTSUPP;
}
static inline int liveupdate_register_flb(struct liveupdate_file_handler *fh,
@@ -269,8 +268,8 @@ static inline int liveupdate_register_flb(struct liveupdate_file_handler *fh,
return -EOPNOTSUPP;
}
-static inline int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
- struct liveupdate_flb *flb)
+static inline void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
+ struct liveupdate_flb *flb)
{
return -EOPNOTSUPP;
}
diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
index 6b2b49cb375e..0fe2f8be8bd1 100644
--- a/kernel/liveupdate/luo_file.c
+++ b/kernel/liveupdate/luo_file.c
@@ -907,21 +907,17 @@ int liveupdate_register_file_handler(struct liveupdate_file_handler *fh)
* reverses the operations of liveupdate_register_file_handler().
*
* It ensures safe removal by checking that:
- * No live update session is currently in progress.
* No FLB registered with this file handler.
*
* If the unregistration fails, the internal test state is reverted.
*
- * Return: 0 Success. -EOPNOTSUPP when live update is not enabled. -EBUSY A live
- * update is in progress, can't quiesce live update or FLB is registred with
- * this file handler.
*/
-int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
+void liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
{
- int err = -EBUSY;
+ bool is_empty;
if (!liveupdate_enabled())
- return -EOPNOTSUPP;
+ return;
liveupdate_test_unregister(fh);
@@ -929,18 +925,19 @@ int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh)
goto err_register;
scoped_guard(rwsem_write, &luo_file_handler_lock) {
- if (!list_empty(&ACCESS_PRIVATE(fh, flb_list)))
- goto err_resume;
-
- list_del(&ACCESS_PRIVATE(fh, list));
+ is_empty = list_empty(&ACCESS_PRIVATE(fh, flb_list));
+ if (is_empty)
+ list_del(&ACCESS_PRIVATE(fh, list));
}
luo_session_resume();
- return 0;
+ if (!is_empty) {
+ pr_warn("Failed to unregister file handler '%s': FLB list not empty\n",
+ fh->compatible);
+ liveupdate_test_register(fh);
+ }
+ return;
-err_resume:
- luo_session_resume();
err_register:
liveupdate_test_register(fh);
- return err;
}
diff --git a/kernel/liveupdate/luo_flb.c b/kernel/liveupdate/luo_flb.c
index daa852abdedd..23fa6e0c6083 100644
--- a/kernel/liveupdate/luo_flb.c
+++ b/kernel/liveupdate/luo_flb.c
@@ -436,31 +436,17 @@ int liveupdate_register_flb(struct liveupdate_file_handler *fh,
* the FLB is removed from the global registry and the reference to its
* owner module (acquired during registration) is released.
*
- * Context: This function ensures the session is quiesced (no active FDs
- * being created) during the update. It is typically called from a
- * subsystem's module exit function.
- * Return: 0 on success.
- * -EOPNOTSUPP if live update is disabled.
- * -EBUSY if the live update session is active and cannot be quiesced.
- * -ENOENT if the FLB was not found in the file handler's list.
*/
-int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
- struct liveupdate_flb *flb)
+void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
+ struct liveupdate_flb *flb)
{
struct luo_flb_private *private = luo_flb_get_private(flb);
struct list_head *flb_list = &ACCESS_PRIVATE(fh, flb_list);
struct luo_flb_link *iter;
- int err = -ENOENT;
+ bool found = false;
if (!liveupdate_enabled())
- return -EOPNOTSUPP;
-
- /*
- * Ensure the system is quiescent (no active sessions).
- * This acts as a global lock for unregistration.
- */
- if (!luo_session_quiesce())
- return -EBUSY;
+ return;
guard(rwsem_write)(&luo_flb_lock);
guard(rwsem_write)(&ACCESS_PRIVATE(fh, flb_lock));
@@ -470,15 +456,19 @@ int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
if (iter->flb == flb) {
list_del(&iter->list);
kfree(iter);
- err = 0;
+ found = true;
break;
}
}
- if (err)
- goto err_resume;
+ if (!found) {
+ pr_warn("Failed to unregister FLB '%s': not found in file handler '%s'\n",
+ flb->compatible, fh->compatible);
+ return;
+ }
private->users--;
+
/*
* If this is the last file-handler with which we are registred, remove
* from the global list, and relese module reference.
@@ -487,14 +477,6 @@ int liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
list_del_init(&private->list);
luo_flb_global.count--;
}
-
- luo_session_resume();
-
- return 0;
-
-err_resume:
- luo_session_resume();
- return err;
}
/**
diff --git a/lib/tests/liveupdate.c b/lib/tests/liveupdate.c
index 496d6ef91a30..5b6abf779f87 100644
--- a/lib/tests/liveupdate.c
+++ b/lib/tests/liveupdate.c
@@ -137,16 +137,12 @@ void liveupdate_test_register(struct liveupdate_file_handler *fh)
void liveupdate_test_unregister(struct liveupdate_file_handler *fh)
{
- int err, i;
+ int i;
for (i = 0; i < TEST_NFLBS; i++) {
struct liveupdate_flb *flb = &test_flbs[i];
- err = liveupdate_unregister_flb(fh, flb);
- if (err) {
- pr_err("Failed to unregister %s %pe\n",
- flb->compatible, ERR_PTR(err));
- }
+ liveupdate_unregister_flb(fh, flb);
}
pr_info("Unregistered %d FLBs from file handler: [%s]\n",
--
2.53.0.851.ga537e3e6e9-googHi Pasha,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-nonmm-unstable]
[also build test WARNING on akpm-mm/mm-everything linus/master v7.0-rc4 next-20260316]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Pasha-Tatashin/liveupdate-Protect-file-handler-list-with-rwsem/20260317-105522
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-nonmm-unstable
patch link: https://lore.kernel.org/r/20260317025049.494931-6-pasha.tatashin%40soleen.com
patch subject: [PATCH 5/6] liveupdate: Make unregister functions return void
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260317/202603171111.YBKWkKnp-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260317/202603171111.YBKWkKnp-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603171111.YBKWkKnp-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from kernel/kexec_core.c:18:
>> include/linux/liveupdate.h:274:2: warning: void function 'liveupdate_unregister_flb' should not return a value [-Wreturn-mismatch]
274 | return -EOPNOTSUPP;
| ^ ~~~~~~~~~~~
1 warning generated.
vim +/liveupdate_unregister_flb +274 include/linux/liveupdate.h
cab056f2aae725 Pasha Tatashin 2025-12-18 270
e62bd1ab0687a1 Pasha Tatashin 2026-03-16 271 static inline void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
cab056f2aae725 Pasha Tatashin 2025-12-18 272 struct liveupdate_flb *flb)
cab056f2aae725 Pasha Tatashin 2025-12-18 273 {
cab056f2aae725 Pasha Tatashin 2025-12-18 @274 return -EOPNOTSUPP;
cab056f2aae725 Pasha Tatashin 2025-12-18 275 }
cab056f2aae725 Pasha Tatashin 2025-12-18 276
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Tue, Mar 17, 2026 at 6:11 AM kernel test robot <lkp@intel.com> wrote:
>
> Hi Pasha,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on akpm-mm/mm-nonmm-unstable]
> [also build test WARNING on akpm-mm/mm-everything linus/master v7.0-rc4 next-20260316]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Pasha-Tatashin/liveupdate-Protect-file-handler-list-with-rwsem/20260317-105522
> base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-nonmm-unstable
> patch link: https://lore.kernel.org/r/20260317025049.494931-6-pasha.tatashin%40soleen.com
> patch subject: [PATCH 5/6] liveupdate: Make unregister functions return void
> config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260317/202603171111.YBKWkKnp-lkp@intel.com/config)
> compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260317/202603171111.YBKWkKnp-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202603171111.YBKWkKnp-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> In file included from kernel/kexec_core.c:18:
> >> include/linux/liveupdate.h:274:2: warning: void function 'liveupdate_unregister_flb' should not return a value [-Wreturn-mismatch]
> 274 | return -EOPNOTSUPP;
> | ^ ~~~~~~~~~~~
> 1 warning generated.
Ah, forgot to update these. Will send v2 soon.
Pasha
>
>
> vim +/liveupdate_unregister_flb +274 include/linux/liveupdate.h
>
> cab056f2aae725 Pasha Tatashin 2025-12-18 270
> e62bd1ab0687a1 Pasha Tatashin 2026-03-16 271 static inline void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
> cab056f2aae725 Pasha Tatashin 2025-12-18 272 struct liveupdate_flb *flb)
> cab056f2aae725 Pasha Tatashin 2025-12-18 273 {
> cab056f2aae725 Pasha Tatashin 2025-12-18 @274 return -EOPNOTSUPP;
> cab056f2aae725 Pasha Tatashin 2025-12-18 275 }
> cab056f2aae725 Pasha Tatashin 2025-12-18 276
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
Hi Pasha,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-nonmm-unstable]
[also build test ERROR on akpm-mm/mm-everything linus/master v7.0-rc4 next-20260316]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Pasha-Tatashin/liveupdate-Protect-file-handler-list-with-rwsem/20260317-105522
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-nonmm-unstable
patch link: https://lore.kernel.org/r/20260317025049.494931-6-pasha.tatashin%40soleen.com
patch subject: [PATCH 5/6] liveupdate: Make unregister functions return void
config: x86_64-rhel-9.4-ltp (https://download.01.org/0day-ci/archive/20260317/202603170941.c2zUXqhx-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260317/202603170941.c2zUXqhx-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603170941.c2zUXqhx-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from kernel/kexec_core.c:18:
include/linux/liveupdate.h: In function 'liveupdate_unregister_flb':
>> include/linux/liveupdate.h:274:16: error: 'return' with a value, in function returning void [-Wreturn-mismatch]
274 | return -EOPNOTSUPP;
| ^
include/linux/liveupdate.h:271:20: note: declared here
271 | static inline void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
| ^~~~~~~~~~~~~~~~~~~~~~~~~
vim +/return +274 include/linux/liveupdate.h
cab056f2aae725 Pasha Tatashin 2025-12-18 270
e62bd1ab0687a1 Pasha Tatashin 2026-03-16 271 static inline void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
cab056f2aae725 Pasha Tatashin 2025-12-18 272 struct liveupdate_flb *flb)
cab056f2aae725 Pasha Tatashin 2025-12-18 273 {
cab056f2aae725 Pasha Tatashin 2025-12-18 @274 return -EOPNOTSUPP;
cab056f2aae725 Pasha Tatashin 2025-12-18 275 }
cab056f2aae725 Pasha Tatashin 2025-12-18 276
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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