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sunrpc: add a Kconfig option to redirect dfprintk() output to trace buffer

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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@kernel.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
This commit is contained in:
Jeff Layton
2025-08-22 09:19:23 -04:00
committed by Anna Schumaker
parent 9082aae154
commit ec7d8e68ef
2 changed files with 22 additions and 2 deletions
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10
include/linux/sunrpc/debug.h
View File

@@ -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, ...) printk(KERN_DEFAULT fmt, ##__VA_ARGS__)
# 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)

14
net/sunrpc/Kconfig
View File

@@ -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