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From: Petr Mladek <pmladek@suse.com>
To: Jiri Kosina <jikos@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Miroslav Benes <mbenes@suse.cz>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
	Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
	Nicolai Stange <nstange@suse.de>,
	live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
	Petr Mladek <pmladek@suse.com>
Subject: [POC 10/23] livepatch: Handle modprobe exit code
Date: Fri, 17 Jan 2020 16:03:10 +0100
Message-ID: <20200117150323.21801-11-pmladek@suse.com> (raw)
In-Reply-To: <20200117150323.21801-1-pmladek@suse.com>

request_module() returns classic negative error codes when it was
not even able to call "modprobe" from some reasons. Otherwise,
it returns the exit code multiplied by 256.

modprobe exit code is always 1 in case of error. Use -EINVAL
instead as the least ugly internal error code.

A better solution would be to somehow pass the original error
code from the init_module() syscall or at least the error code
from klp_module_add() functions. But there is no obvious way
how to pass the information.

Global variable is not enough because more livepatch modules
can be loaded simultaneously from klp_enable_patch() and
klp_module_comming().

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 kernel/livepatch/core.c                             | 3 +++
 tools/testing/selftests/livepatch/test-callbacks.sh | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 8e693c58b736..19ca8baa2f16 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1109,6 +1109,9 @@ static int klp_try_load_object(const char *patch_name, const char *obj_name)
 
 	ret = request_module("%s__%s", patch_name, obj_name);
 	if (ret) {
+		/* modprobe always set exit code 1 on error */
+		if (ret > 0)
+			ret = -EINVAL;
 		pr_info("Module load failed: %s__%s\n", patch_name, obj_name);
 		return ret;
 	}
diff --git a/tools/testing/selftests/livepatch/test-callbacks.sh b/tools/testing/selftests/livepatch/test-callbacks.sh
index 39a4f35e5f8e..060e5b512367 100755
--- a/tools/testing/selftests/livepatch/test-callbacks.sh
+++ b/tools/testing/selftests/livepatch/test-callbacks.sh
@@ -331,7 +331,7 @@ $MOD_LIVEPATCH: pre_patch_callback: $MOD_TARGET -> [MODULE_STATE_COMING] Full fo
 livepatch: pre-patch callback failed for object '$MOD_TARGET'
 livepatch: patch '$MOD_LIVEPATCH' failed for module '$MOD_TARGET', refusing to load module '$MOD_TARGET'
 livepatch: Module load failed: ${MOD_LIVEPATCH}__${MOD_TARGET}
-modprobe: ERROR: could not insert '$MOD_TARGET': No such device
+modprobe: ERROR: could not insert '$MOD_TARGET': Invalid argument
 % echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
 livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
 $MOD_LIVEPATCH: pre_unpatch_callback: vmlinux
-- 
2.16.4


  parent reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-17 15:03 [POC 00/23] livepatch: Split livepatch module per-object Petr Mladek
2020-01-17 15:03 ` [POC 01/23] module: Allow to delete module also from inside kernel Petr Mladek
2020-01-21 11:11   ` Julien Thierry
2020-01-17 15:03 ` [POC 02/23] livepatch: Split livepatch modules per livepatched object Petr Mladek
2020-01-21 11:11   ` Julien Thierry
2020-01-28 12:16     ` Petr Mladek
2020-01-17 15:03 ` [POC 03/23] livepatch: Better checks of struct klp_object definition Petr Mladek
2020-01-21 11:27   ` Julien Thierry
2020-01-17 15:03 ` [POC 04/23] livepatch: Prevent loading livepatch sub-module unintentionally Petr Mladek
2020-04-03 17:54   ` Joe Lawrence
2020-01-17 15:03 ` [POC 05/23] livepatch: Initialize and free livepatch submodule Petr Mladek
2020-01-21 11:58   ` Julien Thierry
2020-01-17 15:03 ` [POC 06/23] livepatch: Enable the " Petr Mladek
2020-01-17 15:03 ` [POC 07/23] livepatch: Remove obsolete functionality from klp_module_coming() Petr Mladek
2020-01-17 15:03 ` [POC 08/23] livepatch: Automatically load livepatch module when the patch module is loaded Petr Mladek
2020-01-17 15:03 ` [POC 09/23] livepatch: Handle race when livepatches are reloaded during a module load Petr Mladek
2020-01-22 18:51   ` Julien Thierry
2020-01-17 15:03 ` Petr Mladek [this message]
2020-01-17 15:03 ` [POC 11/23] livepatch: Safely detect forced transition when removing split livepatch modules Petr Mladek
2020-01-22 10:15   ` Julien Thierry
2020-01-17 15:03 ` [POC 12/23] livepatch: Automatically remove livepatch module when the object is freed Petr Mladek
2020-01-17 15:03 ` [POC 13/23] livepatch: Remove livepatch module when the livepatched module is unloaded Petr Mladek
2020-01-17 15:03 ` [POC 14/23] livepatch: Never block livepatch modules when the related module is being removed Petr Mladek
2020-01-17 15:03 ` [POC 15/23] livepatch: Prevent infinite loop when loading livepatch module Petr Mladek
2020-01-17 15:03 ` [POC 16/23] livepatch: Add patch into the global list early Petr Mladek
2020-01-17 15:03 ` [POC 17/23] livepatch: Load livepatches for modules when loading the main livepatch Petr Mladek
2020-01-17 15:03 ` [POC 18/23] module: Refactor add_unformed_module() Petr Mladek
2020-01-17 15:03 ` [POC 19/23] module/livepatch: Allow to use exported symbols from livepatch module for "vmlinux" Petr Mladek
2020-04-06 18:48   ` Joe Lawrence
2020-04-07  7:33     ` Miroslav Benes
2020-01-17 15:03 ` [POC 20/23] module/livepatch: Relocate local variables in the module loaded when the livepatch is being loaded Petr Mladek
2020-01-18 10:29   ` kbuild test robot
2020-04-03 18:00   ` Joe Lawrence
2020-01-17 15:03 ` [POC 21/23] livepatch: Remove obsolete arch_klp_init_object_loaded() Petr Mladek
2020-01-17 15:03 ` [POC 22/23] livepatch/module: Remove obsolete copy_module_elf() Petr Mladek
2020-04-03 18:03   ` Joe Lawrence
2020-01-17 15:03 ` [POC 23/23] module: Remove obsolete module_disable_ro() Petr Mladek

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