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Message-ID: <alpine.DEB.2.10.1312191136100.13856@nuc>
Date: Thu, 19 Dec 2013 11:37:15 -0600 (CST)
From: Christoph Lameter <cl@...ux.com>
To: David Daney <ddaney.cavm@...il.com>
cc: Tejun Heo <tj@...nel.org>, akpm@...uxfoundation.org,
rostedt@...dmis.org, linux-kernel@...r.kernel.org,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 18/40] percpu: Add preemption checks to __this_cpu ops
On Thu, 19 Dec 2013, David Daney wrote:
> Applying: percpu: Add preemption checks to __this_cpu ops
> /home/ddaney/base/octeon/linux-base/trunk/kernel/linux-master/.git/rebase-apply/patch:139:
> new blank line at EOF.
> +
> warning: 1 line adds whitespace errors.
Ok. Patch that drops the final line:
Subject: percpu: Add preemption checks to __this_cpu ops
[Patch depends on another patch in this series that introduces raw_cpu_ops]
We define a check function in order to avoid trouble with the
include files. Then the higher level __this_cpu macros are
modified to invoke the preemption check.
Acked-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Christoph Lameter <cl@...ux.com>
Index: linux/include/linux/percpu.h
===================================================================
--- linux.orig/include/linux/percpu.h 2013-12-19 11:35:44.171220808 -0600
+++ linux/include/linux/percpu.h 2013-12-19 11:35:44.171220808 -0600
@@ -172,6 +172,12 @@
extern void __bad_size_call_parameter(void);
+#ifdef CONFIG_DEBUG_PREEMPT
+extern void __this_cpu_preempt_check(const char *op);
+#else
+static inline void __this_cpu_preempt_check(const char *op) { }
+#endif
+
#define __pcpu_size_call_return(stem, variable) \
({ typeof(variable) pscr_ret__; \
__verify_pcpu_ptr(&(variable)); \
@@ -724,18 +730,24 @@
/*
* Generic percpu operations for context that are safe from preemption/interrupts.
- * Checks will be added here soon.
*/
#ifndef __this_cpu_read
-# define __this_cpu_read(pcp) __pcpu_size_call_return(raw_cpu_read_, (pcp))
+# define __this_cpu_read(pcp) \
+ (__this_cpu_preempt_check("read"),__pcpu_size_call_return(raw_cpu_read_, (pcp)))
#endif
#ifndef __this_cpu_write
-# define __this_cpu_write(pcp, val) __pcpu_size_call(raw_cpu_write_, (pcp), (val))
+# define __this_cpu_write(pcp, val) \
+do { __this_cpu_preempt_check("write"); \
+ __pcpu_size_call(raw_cpu_write_, (pcp), (val)); \
+} while (0)
#endif
#ifndef __this_cpu_add
-# define __this_cpu_add(pcp, val) __pcpu_size_call(raw_cpu_add_, (pcp), (val))
+# define __this_cpu_add(pcp, val) \
+do { __this_cpu_preempt_check("add"); \
+ __pcpu_size_call(raw_cpu_add_, (pcp), (val)); \
+} while (0)
#endif
#ifndef __this_cpu_sub
@@ -751,16 +763,23 @@
#endif
#ifndef __this_cpu_and
-# define __this_cpu_and(pcp, val) __pcpu_size_call(raw_cpu_and_, (pcp), (val))
+# define __this_cpu_and(pcp, val) \
+do { __this_cpu_preempt_check("and"); \
+ __pcpu_size_call(raw_cpu_and_, (pcp), (val)); \
+} while (0)
+
#endif
#ifndef __this_cpu_or
-# define __this_cpu_or(pcp, val) __pcpu_size_call(raw_cpu_or_, (pcp), (val))
+# define __this_cpu_or(pcp, val) \
+do { __this_cpu_preempt_check("or"); \
+ __pcpu_size_call(raw_cpu_or_, (pcp), (val)); \
+} while (0)
#endif
#ifndef __this_cpu_add_return
# define __this_cpu_add_return(pcp, val) \
- __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val)
+ (__this_cpu_preempt_check("add_return"),__pcpu_size_call_return2(raw_cpu_add_return_, pcp, val))
#endif
#define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val))
@@ -769,17 +788,17 @@
#ifndef __this_cpu_xchg
# define __this_cpu_xchg(pcp, nval) \
- __pcpu_size_call_return2(raw_cpu_xchg_, (pcp), nval)
+ (__this_cpu_preempt_check("xchg"),__pcpu_size_call_return2(raw_cpu_xchg_, (pcp), nval))
#endif
#ifndef __this_cpu_cmpxchg
# define __this_cpu_cmpxchg(pcp, oval, nval) \
- __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
+ (__this_cpu_preempt_check("cmpxchg"),__pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval))
#endif
#ifndef __this_cpu_cmpxchg_double
# define __this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
- __pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2))
+ (__this_cpu_preempt_check("cmpxchg_double"),__pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2)))
#endif
#endif /* __LINUX_PERCPU_H */
Index: linux/lib/smp_processor_id.c
===================================================================
--- linux.orig/lib/smp_processor_id.c 2013-12-19 11:35:44.171220808 -0600
+++ linux/lib/smp_processor_id.c 2013-12-19 11:36:06.110597585 -0600
@@ -7,7 +7,7 @@
#include <linux/kallsyms.h>
#include <linux/sched.h>
-notrace unsigned int debug_smp_processor_id(void)
+notrace static unsigned int check_preemption_disabled(char *what)
{
int this_cpu = raw_smp_processor_id();
@@ -38,9 +38,9 @@
if (!printk_ratelimit())
goto out_enable;
- printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] "
- "code: %s/%d\n",
- preempt_count() - 1, current->comm, current->pid);
+ printk(KERN_ERR "BUG: using %s in preemptible [%08x] code: %s/%d\n",
+ what, preempt_count() - 1, current->comm, current->pid);
+
print_symbol("caller is %s\n", (long)__builtin_return_address(0));
dump_stack();
@@ -50,5 +50,17 @@
return this_cpu;
}
+notrace unsigned int debug_smp_processor_id(void)
+{
+ return check_preemption_disabled("smp_processor_id()");
+}
EXPORT_SYMBOL(debug_smp_processor_id);
+notrace void __this_cpu_preempt_check(const char *op)
+{
+ char text[40];
+
+ snprintf(text, sizeof(text), "__this_cpu_%s()", op);
+ check_preemption_disabled(text);
+}
+EXPORT_SYMBOL(__this_cpu_preempt_check);
--
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