On 8/21/25 3:51 PM, Jeff Layton wrote:
> On Thu, 2025-08-21 at 15:44 -0400, Anna Schumaker wrote:
>> Hi Jeff,
>>
>> On 8/21/25 1:16 PM, Jeff Layton wrote:
>>> We have a lot of old dprintk() call sites that aren't going anywhere
>>> anytime soon. At the same time, turning them up is a serious burden on
>>> the host due to the console locking overhead.
>>>
>>> Add a new Kconfig option that redirects dfprintk() output to the trace
>>> buffer. This is more efficient than logging to the console and allows
>>> for proper interleaving of dprintk and static tracepoint events.
>>>
>>> Since using trace_printk() causes scary warnings to pop at boot time,
>>> this new option defaults to "n".
>>>
>>> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>>> ---
>>> include/linux/sunrpc/debug.h | 10 ++++++++--
>>> net/sunrpc/Kconfig | 14 ++++++++++++++
>>> 2 files changed, 22 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
>>> index 99a6fa4a1d6af0b275546a53957f07c9a509f2ac..fd9f79fa534ef001b3ec5e6d7e4b1099843b64a4 100644
>>> --- a/include/linux/sunrpc/debug.h
>>> +++ b/include/linux/sunrpc/debug.h
>>> @@ -30,17 +30,23 @@ extern unsigned int nlm_debug;
>>> #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
>>> # define ifdebug(fac) if (unlikely(rpc_debug & RPCDBG_##fac))
>>>
>>> +# if IS_ENABLED(CONFIG_SUNRPC_DEBUG_TRACE)
>>> +# define __sunrpc_printk(fmt, ...) trace_printk(fmt, ##__VA_ARGS__)
>>> +# else
>>> +# define __sunrpc_printk(fmt, ...) pr_default(fmt, ##__VA_ARGS__)
>>
>> This is the only reference I can find to "pr_default()" in my tree, and my compiler isn't
>> very happy about it. Am I missing a patch somewhere?
>>
>> Thanks,
>> Anna
>>
>
> No, my apologies. I had made a change in my test branch and didn't pick
> it back into my send branch. That should be:
>
> # define __sunrpc_printk(fmt, ...) printk(KERN_DEFAULT fmt, ##__VA_ARGS__)
>
> I can resend if you are amenable to this patch.
Yes, please do resend!
Thanks,
Anna
>
>>> +# endif
>>> +
>>> # define dfprintk(fac, fmt, ...) \
>>> do { \
>>> ifdebug(fac) \
>>> - printk(KERN_DEFAULT fmt, ##__VA_ARGS__); \
>>> + __sunrpc_printk(fmt, ##__VA_ARGS__); \
>>> } while (0)
>>>
>>> # define dfprintk_rcu(fac, fmt, ...) \
>>> do { \
>>> ifdebug(fac) { \
>>> rcu_read_lock(); \
>>> - printk(KERN_DEFAULT fmt, ##__VA_ARGS__); \
>>> + __sunrpc_printk(fmt, ##__VA_ARGS__); \
>>> rcu_read_unlock(); \
>>> } \
>>> } while (0)
>>> diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
>>> index 2d8b67dac7b5b58a8a86c3022dd573746fb22547..a570e7adf270fb8976f751266bbffe39ef696c6a 100644
>>> --- a/net/sunrpc/Kconfig
>>> +++ b/net/sunrpc/Kconfig
>>> @@ -101,6 +101,20 @@ config SUNRPC_DEBUG
>>>
>>> If unsure, say Y.
>>>
>>> +config SUNRPC_DEBUG_TRACE
>>> + bool "RPC: Send dfprintk() output to the trace buffer"
>>> + depends on SUNRPC_DEBUG && TRACING
>>> + default n
>>> + help
>>> + dprintk() output can be voluminous, which can overwhelm the
>>> + kernel's logging facility as it must be sent to the console.
>>> + This option causes dprintk() output to go to the trace buffer
>>> + instead of the kernel log.
>>> +
>>> + This will cause warnings about trace_printk() being used to be
>>> + logged at boot time, so say N unless you are debugging a problem
>>> + with sunrpc-based clients or services.
>>> +
>>> config SUNRPC_XPRT_RDMA
>>> tristate "RPC-over-RDMA transport"
>>> depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS
>>>
>
