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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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f23eb2b2b2
Using delayed-work for tty flip buffers ends up causing us to wait for the next tick to complete some actions. That's usually not all that noticeable, but for certain latency-critical workloads it ends up being totally unacceptable. As an extreme case of this, passing a token back-and-forth over a pty will take two ticks per iteration, so even just a thousand iterations will take 8 seconds assuming a common 250Hz configuration. Avoiding the whole delayed work issue brings that ping-pong test-case down to 0.009s on my machine. In more practical terms, this latency has been a performance problem for things like dive computer simulators (simulating the serial interface using the ptys) and for other environments (Alan mentions a CP/M emulator). Reported-by: Jef Driesen <jefdriesen@telenet.be> Acked-by: Greg KH <gregkh@suse.de> Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
165 lines
4.3 KiB
C
165 lines
4.3 KiB
C
#ifndef _KBD_KERN_H
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#define _KBD_KERN_H
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#include <linux/tty.h>
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#include <linux/interrupt.h>
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#include <linux/keyboard.h>
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extern struct tasklet_struct keyboard_tasklet;
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extern int shift_state;
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extern char *func_table[MAX_NR_FUNC];
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extern char func_buf[];
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extern char *funcbufptr;
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extern int funcbufsize, funcbufleft;
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/*
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* kbd->xxx contains the VC-local things (flag settings etc..)
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*
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* Note: externally visible are LED_SCR, LED_NUM, LED_CAP defined in kd.h
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* The code in KDGETLED / KDSETLED depends on the internal and
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* external order being the same.
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*
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* Note: lockstate is used as index in the array key_map.
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*/
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struct kbd_struct {
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unsigned char lockstate;
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/* 8 modifiers - the names do not have any meaning at all;
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they can be associated to arbitrarily chosen keys */
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#define VC_SHIFTLOCK KG_SHIFT /* shift lock mode */
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#define VC_ALTGRLOCK KG_ALTGR /* altgr lock mode */
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#define VC_CTRLLOCK KG_CTRL /* control lock mode */
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#define VC_ALTLOCK KG_ALT /* alt lock mode */
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#define VC_SHIFTLLOCK KG_SHIFTL /* shiftl lock mode */
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#define VC_SHIFTRLOCK KG_SHIFTR /* shiftr lock mode */
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#define VC_CTRLLLOCK KG_CTRLL /* ctrll lock mode */
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#define VC_CTRLRLOCK KG_CTRLR /* ctrlr lock mode */
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unsigned char slockstate; /* for `sticky' Shift, Ctrl, etc. */
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unsigned char ledmode:2; /* one 2-bit value */
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#define LED_SHOW_FLAGS 0 /* traditional state */
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#define LED_SHOW_IOCTL 1 /* only change leds upon ioctl */
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#define LED_SHOW_MEM 2 /* `heartbeat': peek into memory */
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unsigned char ledflagstate:4; /* flags, not lights */
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unsigned char default_ledflagstate:4;
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#define VC_SCROLLOCK 0 /* scroll-lock mode */
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#define VC_NUMLOCK 1 /* numeric lock mode */
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#define VC_CAPSLOCK 2 /* capslock mode */
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#define VC_KANALOCK 3 /* kanalock mode */
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unsigned char kbdmode:3; /* one 3-bit value */
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#define VC_XLATE 0 /* translate keycodes using keymap */
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#define VC_MEDIUMRAW 1 /* medium raw (keycode) mode */
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#define VC_RAW 2 /* raw (scancode) mode */
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#define VC_UNICODE 3 /* Unicode mode */
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#define VC_OFF 4 /* disabled mode */
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unsigned char modeflags:5;
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#define VC_APPLIC 0 /* application key mode */
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#define VC_CKMODE 1 /* cursor key mode */
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#define VC_REPEAT 2 /* keyboard repeat */
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#define VC_CRLF 3 /* 0 - enter sends CR, 1 - enter sends CRLF */
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#define VC_META 4 /* 0 - meta, 1 - meta=prefix with ESC */
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};
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extern struct kbd_struct kbd_table[];
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extern int kbd_init(void);
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extern unsigned char getledstate(void);
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extern void setledstate(struct kbd_struct *kbd, unsigned int led);
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extern int do_poke_blanked_console;
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extern void (*kbd_ledfunc)(unsigned int led);
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extern int set_console(int nr);
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extern void schedule_console_callback(void);
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static inline void set_leds(void)
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{
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tasklet_schedule(&keyboard_tasklet);
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}
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static inline int vc_kbd_mode(struct kbd_struct * kbd, int flag)
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{
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return ((kbd->modeflags >> flag) & 1);
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}
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static inline int vc_kbd_led(struct kbd_struct * kbd, int flag)
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{
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return ((kbd->ledflagstate >> flag) & 1);
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}
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static inline void set_vc_kbd_mode(struct kbd_struct * kbd, int flag)
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{
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kbd->modeflags |= 1 << flag;
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}
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static inline void set_vc_kbd_led(struct kbd_struct * kbd, int flag)
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{
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kbd->ledflagstate |= 1 << flag;
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}
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static inline void clr_vc_kbd_mode(struct kbd_struct * kbd, int flag)
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{
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kbd->modeflags &= ~(1 << flag);
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}
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static inline void clr_vc_kbd_led(struct kbd_struct * kbd, int flag)
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{
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kbd->ledflagstate &= ~(1 << flag);
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}
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static inline void chg_vc_kbd_lock(struct kbd_struct * kbd, int flag)
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{
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kbd->lockstate ^= 1 << flag;
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}
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static inline void chg_vc_kbd_slock(struct kbd_struct * kbd, int flag)
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{
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kbd->slockstate ^= 1 << flag;
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}
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static inline void chg_vc_kbd_mode(struct kbd_struct * kbd, int flag)
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{
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kbd->modeflags ^= 1 << flag;
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}
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static inline void chg_vc_kbd_led(struct kbd_struct * kbd, int flag)
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{
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kbd->ledflagstate ^= 1 << flag;
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}
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#define U(x) ((x) ^ 0xf000)
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#define BRL_UC_ROW 0x2800
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/* keyboard.c */
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struct console;
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int getkeycode(unsigned int scancode);
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int setkeycode(unsigned int scancode, unsigned int keycode);
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void compute_shiftstate(void);
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/* defkeymap.c */
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extern unsigned int keymap_count;
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/* console.c */
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static inline void con_schedule_flip(struct tty_struct *t)
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{
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unsigned long flags;
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spin_lock_irqsave(&t->buf.lock, flags);
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if (t->buf.tail != NULL)
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t->buf.tail->commit = t->buf.tail->used;
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spin_unlock_irqrestore(&t->buf.lock, flags);
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schedule_work(&t->buf.work);
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}
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#endif
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