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Remove the global lock and the documentation for it. It was specific to the tty

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driver and doesn't apply to the generic module.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@42086 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Lotz 2011-06-10 17:12:51 +00:00
parent 9254b0c4df
commit 6e72f897f4
3 changed files with 5 additions and 19 deletions
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1
src/add-ons/kernel/generic/tty/module.cpp
View File

@ -68,6 +68,7 @@ static struct tty_module_info sTTYModule = {
0, //B_KEEP_LOADED,
tty_module_std_ops
},
&tty_create,
&tty_destroy,
&tty_create_cookie,

22
src/add-ons/kernel/generic/tty/tty.cpp
View File

@ -41,14 +41,9 @@
Locking
-------
There are four locks involved. If more than one needs to be held at a
There are three locks involved. If more than one needs to be held at a
time, they must be acquired in the order they are listed here.
gGlobalTTYLock: Guards open/close operations. When held, tty_open(),
tty_close(), tty_close_cookie() etc. won't be invoked by other threads,
cookies won't be added to/removed from TTYs, and tty::ref_count,
tty::open_count, tty_cookie::closed won't change.
gTTYCookieLock: Guards the access to the fields
tty_cookie::{thread_count,closed}, or more precisely makes access to them
atomic. thread_count is the number of threads currently using the cookie
@ -59,9 +54,8 @@
tty::lock: Guards the access to tty::{input_buffer,settings::{termios,
window_size,pgrp_id}}. Moreover when held guarantees that tty::open_count
won't drop to zero (both gGlobalTTYLock and tty::lock must be held to
decrement it). A tty and the tty connected to it (master and slave) share
the same lock.
won't drop to zero. A tty and the tty connected to it (master and slave)
share the same lock.
gTTYRequestLock: Guards access to tty::{reader,writer}_queue (most
RequestQueue methods do the locking themselves (the lock is a
@ -863,8 +857,6 @@ tty_input_putc(struct tty* tty, int c)
#endif // 0
/*! The global lock must be held.
*/
tty_cookie*
tty_create_cookie(struct tty* tty, struct tty* otherTTY, uint32 openMode)
{
@ -896,8 +888,6 @@ tty_create_cookie(struct tty* tty, struct tty* otherTTY, uint32 openMode)
}
/*! The global lock must be held.
*/
void
tty_destroy_cookie(tty_cookie* cookie)
{
@ -917,8 +907,6 @@ tty_destroy_cookie(tty_cookie* cookie)
}
/*! The global lock must be held.
*/
void
tty_close_cookie(tty_cookie* cookie)
{
@ -958,9 +946,7 @@ tty_close_cookie(tty_cookie* cookie)
// For the removal of the cookie acquire the TTY's lock. This ensures, that
// cookies will not be removed from a TTY (or added -- cf. add_tty_cookie())
// as long as the TTY's lock is being held. This is required for the select
// support, since we need to iterate through the cookies of a TTY without
// having to acquire the global lock.
// as long as the TTY's lock is being held.
MutexLocker ttyLocker(cookie->tty->lock);
// remove the cookie from the TTY's cookie list

1
src/add-ons/kernel/generic/tty/tty_private.h
View File

@ -142,7 +142,6 @@ struct tty {
};
extern struct mutex gGlobalTTYLock;
extern struct mutex gTTYCookieLock;
extern struct recursive_lock gTTYRequestLock;