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Date: Thu, 7 Jan 2021 19:08:58 +0800
From: Yejune Deng <yejune.deng@...il.com>
To: Steve French <smfrench@...il.com>
Cc: Steve French <sfrench@...ba.org>,
CIFS <linux-cifs@...r.kernel.org>,
samba-technical <samba-technical@...ts.samba.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cifs: fix msleep() is imprecise
No。I just see Documentation/timers/timers-howto.rst and don't
recommend using msleep() for (1ms - 20ms). It recommends using
usleep_range(). And fsleep() is flexible sleeping.
On Wed, Jan 6, 2021 at 12:27 PM Steve French <smfrench@...il.com> wrote:
>
> 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@...il.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@...il.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
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