okash.khawaja@xxxxxxxxx, on sam. 11 mars 2017 13:05:25 +0000, wrote: > Allow access to TTY device from kernel. This is based on Alan Cox's patch > (http://www.mail-archive.com/linux-kernel at vger.kernel.org/msg1215095.html), > with description quoted below. > > "tty_port: allow a port to be opened with a tty that has no file handle > > Let us create tty objects entirely in kernel space. > > With this a kernel created non file backed tty object could be used to handle > data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in > particular has to work back to the fs/tty layer. > > The tty_port code is however otherwise clean of file handles as far as I can > tell as is the low level tty port write path used by the ldisc, the > configuration low level interfaces and most of the ldiscs. > > Currently you don't have any exposure to see tty hangups because those are > built around the file layer. However a) it's a fixed port so you probably > don't care about that b) if you do we can add a callback and c) you almost > certainly don't want the userspace tear down/rebuild behaviour anyway. > > This should however be sufficient if we wanted for example to enumerate all > the bluetooth bound fixed ports via ACPI and make them directly available. > > It doesn't deal with the case of a user opening a port that's also kernel > opened and that would need some locking out (so it returned EBUSY if bound > to a kernel device of some kind). That needs resolving along with how you > "up" or "down" your new bluetooth device, or enumerate it while providing > the existing tty API to avoid regressions (and to debug)." > > Signed-off-by: Okash Khawaja <okash.khawaja@xxxxxxxxx> Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx> > Index: linux-4.10.1/drivers/tty/tty_io.c > =================================================================== > --- linux-4.10.1.orig/drivers/tty/tty_io.c > +++ linux-4.10.1/drivers/tty/tty_io.c > @@ -855,7 +855,7 @@ > > int tty_hung_up_p(struct file *filp) > { > - return (filp->f_op == &hung_up_tty_fops); > + return (filp && filp->f_op == &hung_up_tty_fops); > } > > EXPORT_SYMBOL(tty_hung_up_p); > @@ -1368,7 +1368,10 @@ > struct tty_struct *tty; > > if (driver->ops->lookup) > - tty = driver->ops->lookup(driver, file, idx); > + if (!file) > + tty = ERR_PTR(-EIO); > + else > + tty = driver->ops->lookup(driver, file, idx); > else > tty = driver->ttys[idx]; > > @@ -1986,7 +1989,7 @@ > struct tty_driver *console_driver = console_device(index); > if (console_driver) { > driver = tty_driver_kref_get(console_driver); > - if (driver) { > + if (driver && filp) { > /* Don't let /dev/console block */ > filp->f_flags |= O_NONBLOCK; > break; > @@ -2019,7 +2022,7 @@ > * - concurrent tty driver removal w/ lookup > * - concurrent tty removal from driver table > */ > -static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, > +struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, > struct file *filp) > { > struct tty_struct *tty; > @@ -2064,6 +2067,7 @@ > tty_driver_kref_put(driver); > return tty; > } > +EXPORT_SYMBOL(tty_open_by_driver); > > /** > * tty_open - open a tty device > Index: linux-4.10.1/drivers/tty/tty_port.c > =================================================================== > --- linux-4.10.1.orig/drivers/tty/tty_port.c > +++ linux-4.10.1/drivers/tty/tty_port.c > @@ -335,7 +335,7 @@ > * tty_port_block_til_ready - Waiting logic for tty open > * @port: the tty port being opened > * @tty: the tty device being bound > - * @filp: the file pointer of the opener > + * @filp: the file pointer of the opener or NULL > * > * Implement the core POSIX/SuS tty behaviour when opening a tty device. > * Handles: > @@ -369,7 +369,7 @@ > tty_port_set_active(port, 1); > return 0; > } > - if (filp->f_flags & O_NONBLOCK) { > + if (filp == NULL || filp->f_flags & O_NONBLOCK) { > /* Indicate we are open */ > if (C_BAUD(tty)) > tty_port_raise_dtr_rts(port); > Index: linux-4.10.1/include/linux/tty.h > =================================================================== > --- linux-4.10.1.orig/include/linux/tty.h > +++ linux-4.10.1/include/linux/tty.h > @@ -394,6 +394,8 @@ > /* tty_io.c */ > extern int __init tty_init(void); > extern const char *tty_name(const struct tty_struct *tty); > +extern struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, > + struct file *filp); > #else > static inline void console_init(void) > { } > -- Samuel > et sinon, quand on s'interesse a un media que l'on ne maitrise pas, > on essaye de le comprendre d'abord. (Suivi par l'intégralité du message initial de 45 lignes.) -+-BM in : GNU - La maîtrise est un long apprentissage petit scarabé -+- _______________________________________________ Speakup mailing list Speakup@xxxxxxxxxxxxxxxxx http://linux-speakup.org/cgi-bin/mailman/listinfo/speakup
