On Thu, Mar 11, 2021 at 12:40:37AM +0300, Vitaliy Makkoveev wrote:
> Since UNIX domain sockets are unlocked it makes sense to unlock
> sys_sendsyslog too. Console output still requires kernel lock to be
> held but this path is only followed while `syslogf' socket is not set.
>
> New `syslogf_rwlock' used to protect `syslogf' access.
>
> ok?
regress passes, OK bluhm@
> Index: sys/kern/subr_log.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/subr_log.c,v
> retrieving revision 1.73
> diff -u -p -r1.73 subr_log.c
> --- sys/kern/subr_log.c 9 Mar 2021 15:08:23 -0000 1.73
> +++ sys/kern/subr_log.c 10 Mar 2021 21:25:24 -0000
> @@ -86,7 +86,9 @@ int log_open; /* also used in log() */
> int msgbufmapped; /* is the message buffer mapped */
> struct msgbuf *msgbufp; /* the mapped buffer, itself. */
> struct msgbuf *consbufp; /* console message buffer. */
> +
> struct file *syslogf;
> +struct rwlock syslogf_rwlock = RWLOCK_INITIALIZER("syslogf");
>
> /*
> * Lock that serializes access to log message buffers.
> @@ -215,8 +217,11 @@ logclose(dev_t dev, int flag, int mode,
> {
> struct file *fp;
>
> + rw_enter_write(&syslogf_rwlock);
> fp = syslogf;
> syslogf = NULL;
> + rw_exit(&syslogf_rwlock);
> +
> if (fp)
> FRELE(fp, p);
> log_open = 0;
> @@ -407,7 +412,7 @@ out:
> int
> logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
> {
> - struct file *fp;
> + struct file *fp, *newfp;
> int error;
>
> switch (com) {
> @@ -441,9 +446,14 @@ logioctl(dev_t dev, u_long com, caddr_t
> case LIOCSFD:
> if ((error = suser(p)) != 0)
> return (error);
> - fp = syslogf;
> - if ((error = getsock(p, *(int *)data, &syslogf)) != 0)
> + if ((error = getsock(p, *(int *)data, &newfp)) != 0)
> return (error);
> +
> + rw_enter_write(&syslogf_rwlock);
> + fp = syslogf;
> + syslogf = newfp;
> + rw_exit(&syslogf_rwlock);
> +
> if (fp)
> FRELE(fp, p);
> break;
> @@ -635,12 +645,15 @@ dosendsyslog(struct proc *p, const char
> int error;
>
> /* Global variable syslogf may change during sleep, use local copy. */
> + rw_enter_read(&syslogf_rwlock);
> fp = syslogf;
> if (fp)
> FREF(fp);
> - else if (!ISSET(flags, LOG_CONS))
> - return (ENOTCONN);
> - else {
> + rw_exit(&syslogf_rwlock);
> +
> + if (fp == NULL) {
> + if (!ISSET(flags, LOG_CONS))
> + return (ENOTCONN);
> /*
> * Strip off syslog priority when logging to console.
> * LOG_PRIMASK | LOG_FACMASK is 0x03ff, so at most 4
> @@ -690,41 +703,45 @@ dosendsyslog(struct proc *p, const char
> error = sosend(fp->f_data, NULL, &auio, NULL, NULL, flags);
> if (error == 0)
> len -= auio.uio_resid;
> - } else if (constty || cn_devvp) {
> - error = cnwrite(0, &auio, 0);
> - if (error == 0)
> - len -= auio.uio_resid;
> - aiov.iov_base = "\r\n";
> - aiov.iov_len = 2;
> - auio.uio_iov = &aiov;
> - auio.uio_iovcnt = 1;
> - auio.uio_segflg = UIO_SYSSPACE;
> - auio.uio_rw = UIO_WRITE;
> - auio.uio_procp = p;
> - auio.uio_offset = 0;
> - auio.uio_resid = aiov.iov_len;
> - cnwrite(0, &auio, 0);
> } else {
> - /* XXX console redirection breaks down... */
> - if (sflg == UIO_USERSPACE) {
> - kbuf = malloc(len, M_TEMP, M_WAITOK);
> - error = copyin(aiov.iov_base, kbuf, len);
> + KERNEL_LOCK();
> + if (constty || cn_devvp) {
> + error = cnwrite(0, &auio, 0);
> + if (error == 0)
> + len -= auio.uio_resid;
> + aiov.iov_base = "\r\n";
> + aiov.iov_len = 2;
> + auio.uio_iov = &aiov;
> + auio.uio_iovcnt = 1;
> + auio.uio_segflg = UIO_SYSSPACE;
> + auio.uio_rw = UIO_WRITE;
> + auio.uio_procp = p;
> + auio.uio_offset = 0;
> + auio.uio_resid = aiov.iov_len;
> + cnwrite(0, &auio, 0);
> } else {
> - kbuf = aiov.iov_base;
> - error = 0;
> - }
> - if (error == 0)
> - for (i = 0; i < len; i++) {
> - if (kbuf[i] == '\0')
> - break;
> - cnputc(kbuf[i]);
> - auio.uio_resid--;
> + /* XXX console redirection breaks down... */
> + if (sflg == UIO_USERSPACE) {
> + kbuf = malloc(len, M_TEMP, M_WAITOK);
> + error = copyin(aiov.iov_base, kbuf, len);
> + } else {
> + kbuf = aiov.iov_base;
> + error = 0;
> }
> - if (sflg == UIO_USERSPACE)
> - free(kbuf, M_TEMP, len);
> - if (error == 0)
> - len -= auio.uio_resid;
> - cnputc('\n');
> + if (error == 0)
> + for (i = 0; i < len; i++) {
> + if (kbuf[i] == '\0')
> + break;
> + cnputc(kbuf[i]);
> + auio.uio_resid--;
> + }
> + if (sflg == UIO_USERSPACE)
> + free(kbuf, M_TEMP, len);
> + if (error == 0)
> + len -= auio.uio_resid;
> + cnputc('\n');
> + }
> + KERNEL_UNLOCK();
> }
>
> #ifdef KTRACE
> Index: sys/kern/syscalls.master
> ===================================================================
> RCS file: /cvs/src/sys/kern/syscalls.master,v
> retrieving revision 1.208
> diff -u -p -r1.208 syscalls.master
> --- sys/kern/syscalls.master 18 Jan 2021 18:25:51 -0000 1.208
> +++ sys/kern/syscalls.master 10 Mar 2021 21:25:25 -0000
> @@ -235,7 +235,7 @@
> fd_set *ex, const struct timespec *ts, \
> const sigset_t *mask); }
> 111 STD { int sys_sigsuspend(int mask); }
> -112 STD { int sys_sendsyslog(const char *buf, size_t nbyte, \
> +112 STD NOLOCK { int sys_sendsyslog(const char *buf, size_t nbyte, \
> int flags); }
> 113 UNIMPL fktrace
> 114 STD { int sys_unveil(const char *path, \
