[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <20240205-cond_guard-v1-1-b8d597a30cdd@intel.com>
Date: Mon, 05 Feb 2024 10:07:23 -0800
From: Ira Weiny <ira.weiny@...el.com>
To: Peter Zijlstra <peterz@...radead.org>,
Dan Williams <dan.j.williams@...el.com>,
"Fabio M. De Francesco" <fabio.maria.de.francesco@...ux.intel.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: Ingo Molnar <mingo@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
Ira Weiny <ira.weiny@...el.com>
Subject: [PATCH RFC] cleanup/scoped_cond_guard: Fix multiple statements in
fail
In attempting to create a cond_guard() macro[1] Fabio asked me to do
some testing of the macros he was creating. The model for this macro
was scoped_cond_guard() and the ability to declare a block for the error
path.
A simple test for scoped_cond_guard() was created to learn how it
worked and to model cond_guard() after it. Specifically compound
statements were tested as suggested to be used in cond_guard().[2]
static int test_scoped_cond_guard(void)
{
scoped_cond_guard(rwsem_write_try,
{ printk(KERN_DEBUG "Failed\n"); return -EINVAL; },
&my_sem) {
printk(KERN_DEBUG "Protected\n");
}
return 0;
}
This test fails with the current code:
lib/test-cleanup.c: In function ‘test_scoped_cond_guard’:
/include/linux/cleanup.h:190:17: error: ‘else’ without a previous ‘if’
190 | else
| ^~~~
lib/test-cleanup.c:79:9: note: in expansion of macro ‘scoped_cond_guard’
79 | scoped_cond_guard(rwsem_write_try,
| ^~~~~~~~~~~~~~~~~
This is due to an extra statement between the if and else blocks created
by the ';' in the macro.
Ensure the if block is delineated properly for the use of compound
statements within the macro.
[1] https://lore.kernel.org/all/20240204173105.935612-1-fabio.maria.de.francesco@linux.intel.com/
[2] https://lore.kernel.org/all/65b938c1ad435_5cc6f294eb@dwillia2-mobl3.amr.corp.intel.com.notmuch/
Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
NOTE: There is no user of this syntax yet but this is the way that Dan
and I thought the macro worked. An alternate syntax would be to require
termination of the statement (ie use ';') in the use of the macro; see
below. But this change seemed better as the compiler should drop the
extra statements created and allows for a bit more flexibility in the
use of the macro.
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 88af56600325..6cc4bfe61bc7 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -186,7 +186,7 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
#define scoped_cond_guard(_name, _fail, args...) \
for (CLASS(_name, scope)(args), \
*done = NULL; !done; done = (void *)1) \
- if (!__guard_ptr(_name)(&scope)) _fail; \
+ if (!__guard_ptr(_name)(&scope)) _fail \
else
/*
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 2fabd497d659..fae110e8b89f 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -441,7 +441,7 @@ static int ptrace_attach(struct task_struct *task, long request,
* SUID, SGID and LSM creds get determined differently
* under ptrace.
*/
- scoped_cond_guard (mutex_intr, return -ERESTARTNOINTR,
+ scoped_cond_guard (mutex_intr, return -ERESTARTNOINTR;,
&task->signal->cred_guard_mutex) {
scoped_guard (task_lock, task) {
---
include/linux/cleanup.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 88af56600325..d45452ce6222 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -186,7 +186,7 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
#define scoped_cond_guard(_name, _fail, args...) \
for (CLASS(_name, scope)(args), \
*done = NULL; !done; done = (void *)1) \
- if (!__guard_ptr(_name)(&scope)) _fail; \
+ if (!__guard_ptr(_name)(&scope)) { _fail; } \
else
/*
---
base-commit: 03c972291873663f15c78ff4ca07cbf5025735f8
change-id: 20240201-cond_guard-afa0566cecdf
Best regards,
--
Ira Weiny <ira.weiny@...el.com>
Powered by blists - more mailing lists