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From:   Steve French <smfrench@gmail.com>
Date:   Tue, 5 Jan 2021 22:26:47 -0600
Message-ID: <CAH2r5mvgjFWwEcqt8nfiU_1GJQUU7jN=eNT-t6SBEK8jke0Msg@mail.gmail.com>
Subject: Re: [PATCH] cifs: fix msleep() is imprecise
To:     Yejune Deng <yejune.deng@gmail.com>
Cc:     Steve French <sfrench@samba.org>,
        CIFS <linux-cifs@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>
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This patch seems reasonable at first glance, but I was a little
concerned that we don't see many users yet of fsleep.  Has there been
pushback on converting "yield" situations from using msleep to fsleep?

On Thu, Dec 10, 2020 at 3:09 AM Yejune Deng <yejune.deng@gmail.com> wrote:
>
> See Documentation/timers/timers-howto.rst, msleep() is not
> for (1ms - 20ms), There is a more advanced API is used.
>
> Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
> ---
>  fs/cifs/cifsfs.c    |  4 ++--
>  fs/cifs/connect.c   | 14 +++++++-------
>  fs/cifs/file.c      |  6 +++---
>  fs/cifs/smbdirect.c |  2 +-
>  4 files changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 472cb77..d35ce52 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -664,10 +664,10 @@ static void cifs_umount_begin(struct super_block *sb)
>                 cifs_dbg(FYI, "wake up tasks now - umount begin not complete\n");
>                 wake_up_all(&tcon->ses->server->request_q);
>                 wake_up_all(&tcon->ses->server->response_q);
> -               msleep(1); /* yield */
> +               fsleep(1000); /* yield */
>                 /* we have to kick the requests once more */
>                 wake_up_all(&tcon->ses->server->response_q);
> -               msleep(1);
> +               fsleep(1000);
>         }
>
>         return;
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 44f9cce..62a9c64 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -538,7 +538,7 @@ static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
>                 if (rc) {
>                         cifs_dbg(FYI, "reconnect error %d\n", rc);
>                         mutex_unlock(&server->srv_mutex);
> -                       msleep(3000);
> +                       ssleep(3);
>                 } else {
>                         atomic_inc(&tcpSesReconnectCount);
>                         set_credits(server, 1);
> @@ -621,7 +621,7 @@ static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
>                 server->bigbuf = (char *)cifs_buf_get();
>                 if (!server->bigbuf) {
>                         cifs_server_dbg(VFS, "No memory for large SMB response\n");
> -                       msleep(3000);
> +                       ssleep(3);
>                         /* retry will check if exiting */
>                         return false;
>                 }
> @@ -634,7 +634,7 @@ static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
>                 server->smallbuf = (char *)cifs_small_buf_get();
>                 if (!server->smallbuf) {
>                         cifs_server_dbg(VFS, "No memory for SMB response\n");
> -                       msleep(1000);
> +                       ssleep(1);
>                         /* retry will check if exiting */
>                         return false;
>                 }
> @@ -729,7 +729,7 @@ static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
>                          * to clear and app threads to set tcpStatus
>                          * CifsNeedReconnect if server hung.
>                          */
> -                       usleep_range(1000, 2000);
> +                       fsleep(1000);
>                         length = 0;
>                         continue;
>                 }
> @@ -790,7 +790,7 @@ static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
>                  */
>                 cifs_dbg(FYI, "RFC 1002 negative session response\n");
>                 /* give server a second to clean up */
> -               msleep(1000);
> +               ssleep(1);
>                 /*
>                  * Always try 445 first on reconnect since we get NACK
>                  * on some if we ever connected to port 139 (the NACK
> @@ -944,7 +944,7 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
>                  * response and going ahead and killing cifsd.
>                  */
>                 cifs_dbg(FYI, "Wait for exit from demultiplex thread\n");
> -               msleep(46000);
> +               ssleep(46);
>                 /*
>                  * If threads still have not exited they are probably never
>                  * coming home not much else we can do but free the memory.
> @@ -3655,7 +3655,7 @@ static void rfc1002mangle(char *target, char *source, unsigned int length)
>                  * significant slowing down on mount
>                  * for everyone else
>                  */
> -               usleep_range(1000, 2000);
> +               fsleep(1000);
>         }
>         /*
>          * else the negprot may still work without this
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index be46fab..75538a8 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -283,7 +283,7 @@ int cifs_posix_open(char *full_path, struct inode **pinode,
>  cifs_down_write(struct rw_semaphore *sem)
>  {
>         while (!down_write_trylock(sem))
> -               msleep(10);
> +               fsleep(10000);
>  }
>
>  static void cifsFileInfo_put_work(struct work_struct *work);
> @@ -2828,7 +2828,7 @@ size_t get_numpages(const size_t wsize, const size_t len, size_t *cur_len)
>
>                         if (wsize < wdata->bytes) {
>                                 add_credits_and_wake_if(server, &credits, 0);
> -                               msleep(1000);
> +                               ssleep(1);
>                         }
>                 } while (wsize < wdata->bytes);
>                 wdata->credits = credits;
> @@ -3563,7 +3563,7 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
>
>                         if (rsize < rdata->bytes) {
>                                 add_credits_and_wake_if(server, &credits, 0);
> -                               msleep(1000);
> +                               ssleep(1);
>                         }
>                 } while (rsize < rdata->bytes);
>                 rdata->credits = credits;
> diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
> index b029ed3..84f97f8 100644
> --- a/fs/cifs/smbdirect.c
> +++ b/fs/cifs/smbdirect.c
> @@ -1372,7 +1372,7 @@ void smbd_destroy(struct TCP_Server_Info *server)
>         wake_up_interruptible_all(&info->wait_mr);
>         while (atomic_read(&info->mr_used_count)) {
>                 mutex_unlock(&server->srv_mutex);
> -               msleep(1000);
> +               ssleep(1);
>                 mutex_lock(&server->srv_mutex);
>         }
>         destroy_mr_list(info);
> --
> 1.9.1
>


-- 
Thanks,

Steve