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
Certain uses of "do once" functionality reside outside of fast path,
and so do not require jump label patching via static keys, making
existing DO_ONCE undesirable in such cases.
Replace uses of __section(".data.once") with DO_ONCE_LITE(_IF)?
This patch changes the return values of xfs_printk_once, printk_once,
and printk_deferred_once. Before, they returned whether the print was
performed, but now, they always return true. This is okay because the
return values of the following macros are entirely ignored throughout
the kernel:
- xfs_printk_once
- xfs_warn_once
- xfs_notice_once
- xfs_info_once
- printk_once
- pr_emerg_once
- pr_alert_once
- pr_crit_once
- pr_err_once
- pr_warn_once
- pr_notice_once
- pr_info_once
- pr_devel_once
- pr_debug_once
- printk_deferred_once
- orc_warn
Changes
v3:
- Expand commit message to explain why changing return values of
xfs_printk_once, printk_once, printk_deferred_once is benign
v2:
- Fix i386 build warnings
Signed-off-by: Tanner Love <tannerlove@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Mahesh Bandewar <maheshb@google.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Peter Zijlstra