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a1a5482a2c
On Fri, Jun 17, 2022 at 02:08:52PM +0300, Stephane Eranian wrote: > Some changes to the way invalid MSR accesses are reported by the > kernel is causing some problems with messages printed on the > console. > > We have seen several cases of ex_handler_msr() printing invalid MSR > accesses once but the callstack multiple times causing confusion on > the console. > The problem here is that another earlier commit (5.13): > >a358f40600("once: implement DO_ONCE_LITE for non-fast-path "do once" functionality") > > Modifies all the pr_*_once() calls to always return true claiming > that no caller is ever checking the return value of the functions. > > This is why we are seeing the callstack printed without the > associated printk() msg. Extract the ONCE_IF(cond) part into __ONCE_LTE_IF() and use that to implement DO_ONCE_LITE_IF() and fix the extable code. Fixes:a358f40600("once: implement DO_ONCE_LITE for non-fast-path "do once" functionality") Reported-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Stephane Eranian <eranian@google.com> Link: https://lkml.kernel.org/r/YqyVFsbviKjVGGZ9@worktop.programming.kicks-ass.net
37 lines
925 B
C
37 lines
925 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_ONCE_LITE_H
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#define _LINUX_ONCE_LITE_H
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#include <linux/types.h>
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/* Call a function once. Similar to DO_ONCE(), but does not use jump label
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* patching via static keys.
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*/
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#define DO_ONCE_LITE(func, ...) \
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DO_ONCE_LITE_IF(true, func, ##__VA_ARGS__)
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#define __ONCE_LITE_IF(condition) \
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({ \
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static bool __section(".data.once") __already_done; \
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bool __ret_cond = !!(condition); \
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bool __ret_once = false; \
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\
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if (unlikely(__ret_cond && !__already_done)) { \
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__already_done = true; \
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__ret_once = true; \
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} \
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unlikely(__ret_once); \
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})
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#define DO_ONCE_LITE_IF(condition, func, ...) \
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({ \
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bool __ret_do_once = !!(condition); \
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\
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if (__ONCE_LITE_IF(__ret_do_once)) \
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func(__VA_ARGS__); \
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\
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unlikely(__ret_do_once); \
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})
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#endif /* _LINUX_ONCE_LITE_H */
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