netdev - Re: [PATCH v2 1/2] sunrpc: remove dfprintk_cont() and dfprintk_rcu

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Message-ID: <126e0fe0-a20a-4460-b9b0-19a63d02667b@oracle.com>
Date: Wed, 27 Aug 2025 10:41:25 -0400
From: Chuck Lever <chuck.lever@...cle.com>
To: Jeff Layton <jlayton@...nel.org>, Trond Myklebust <trondmy@...nel.org>,
        Anna Schumaker <anna@...nel.org>, NeilBrown <neil@...wn.name>,
        Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>,
        Tom Talpey <tom@...pey.com>, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v2 1/2] sunrpc: remove dfprintk_cont() and
 dfprintk_rcu_cont()

On 8/22/25 9:19 AM, Jeff Layton wrote:
> KERN_CONT hails from a simpler time, when SMP wasn't the norm. These
> days, it doesn't quite work right since another printk() can always race
> in between the first one and the one being "continued".
> 
> Nothing calls dprintk_rcu_cont(), so just remove it. The only caller of
> dprintk_cont() is in nfs_commit_release_pages(). Just use a normal
> dprintk() there instead, since this is not SMP-safe anyway.
> 
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
> ---
>  fs/nfs/write.c               |  6 +++---
>  include/linux/sunrpc/debug.h | 24 ++----------------------
>  2 files changed, 5 insertions(+), 25 deletions(-)
> 
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index d881486d235ba042feedd2dd59d6a60b366b9600..4d5699b4a1fabff39e67998af40561620b532db6 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -1862,7 +1862,7 @@ static void nfs_commit_release_pages(struct nfs_commit_data *data)
>  				nfs_mapping_set_error(folio, status);
>  				nfs_inode_remove_request(req);
>  			}
> -			dprintk_cont(", error = %d\n", status);
> +			dprintk(", error = %d\n", status);
>  			goto next;
>  		}
>  
> @@ -1872,11 +1872,11 @@ static void nfs_commit_release_pages(struct nfs_commit_data *data)
>  			/* We have a match */
>  			if (folio)
>  				nfs_inode_remove_request(req);
> -			dprintk_cont(" OK\n");
> +			dprintk(" OK\n");
>  			goto next;
>  		}
>  		/* We have a mismatch. Write the page again */
> -		dprintk_cont(" mismatch\n");
> +		dprintk(" mismatch\n");
>  		nfs_mark_request_dirty(req);
>  		atomic_long_inc(&NFS_I(data->inode)->redirtied_pages);
>  	next:
> diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
> index f6aeed07fe04e3d51d7f9d23b10fe86d36241b45..99a6fa4a1d6af0b275546a53957f07c9a509f2ac 100644
> --- a/include/linux/sunrpc/debug.h
> +++ b/include/linux/sunrpc/debug.h
> @@ -23,12 +23,8 @@ extern unsigned int		nlm_debug;
>  
>  #define dprintk(fmt, ...)						\
>  	dfprintk(FACILITY, fmt, ##__VA_ARGS__)
> -#define dprintk_cont(fmt, ...)						\
> -	dfprintk_cont(FACILITY, fmt, ##__VA_ARGS__)
>  #define dprintk_rcu(fmt, ...)						\
>  	dfprintk_rcu(FACILITY, fmt, ##__VA_ARGS__)
> -#define dprintk_rcu_cont(fmt, ...)					\
> -	dfprintk_rcu_cont(FACILITY, fmt, ##__VA_ARGS__)
>  
>  #undef ifdebug
>  #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
> @@ -37,29 +33,14 @@ extern unsigned int		nlm_debug;
>  # define dfprintk(fac, fmt, ...)					\
>  do {									\
>  	ifdebug(fac)							\
> -		printk(KERN_DEFAULT fmt, ##__VA_ARGS__);		\
> -} while (0)
> -
> -# define dfprintk_cont(fac, fmt, ...)					\
> -do {									\
> -	ifdebug(fac)							\
> -		printk(KERN_CONT fmt, ##__VA_ARGS__);			\
> +		printk(KERN_DEFAULT fmt, ##__VA_ARGS__);				\
>  } while (0)
>  
>  # define dfprintk_rcu(fac, fmt, ...)					\
>  do {									\
>  	ifdebug(fac) {							\
>  		rcu_read_lock();					\
> -		printk(KERN_DEFAULT fmt, ##__VA_ARGS__);		\
> -		rcu_read_unlock();					\
> -	}								\
> -} while (0)
> -
> -# define dfprintk_rcu_cont(fac, fmt, ...)				\
> -do {									\
> -	ifdebug(fac) {							\
> -		rcu_read_lock();					\
> -		printk(KERN_CONT fmt, ##__VA_ARGS__);			\
> +		printk(KERN_DEFAULT fmt, ##__VA_ARGS__);				\
>  		rcu_read_unlock();					\
>  	}								\
>  } while (0)
> @@ -68,7 +49,6 @@ do {									\
>  #else
>  # define ifdebug(fac)		if (0)
>  # define dfprintk(fac, fmt, ...)	do {} while (0)
> -# define dfprintk_cont(fac, fmt, ...)	do {} while (0)
>  # define dfprintk_rcu(fac, fmt, ...)	do {} while (0)
>  # define RPC_IFDEBUG(x)
>  #endif
> 

Reviewed-by: Chuck Lever <chuck.lever@...cle.com>

-- 
Chuck Lever