tty: Add a new VT mode which is like VT_PROCESS but doesn't require a VT_RELDISP ioctl call
This new VT mode (VT_PROCESS_AUTO) does everything that VT_PROCESS does except that it doesn't wait for a VT_RELDISP ioctl before switching away from a VT with that mode. If the X server eventually uses this new mode, debugging and crash recovery should become easier. This is because even when currently in the VT of a frozen X server it would still be possible to switch out by doing SysRq-r and then CTRL-<number of a text vt>, sshing in and doing chvt <number of a text vt>, or any other method of VT switching. The general concensus on #xorg-devel seems to be that it should be safe to use this with X now that we have KMS. This also moves the VT_ACKACQ define to a more appropriate place, for clarity's sake. Signed-off-by: Ari Entlich <atrigent@ccs.neu.edu> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -888,7 +888,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
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ret = -EFAULT;
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goto out;
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}
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if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS) {
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if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS && tmp.mode != VT_PROCESS_AUTO) {
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ret = -EINVAL;
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goto out;
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}
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@ -1622,7 +1622,7 @@ static void complete_change_console(struct vc_data *vc)
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* telling it that it has acquired. Also check if it has died and
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* clean up (similar to logic employed in change_console())
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*/
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if (vc->vt_mode.mode == VT_PROCESS) {
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if (vc->vt_mode.mode == VT_PROCESS || vc->vt_mode.mode == VT_PROCESS_AUTO) {
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/*
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* Send the signal as privileged - kill_pid() will
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* tell us if the process has gone or something else
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@ -1682,7 +1682,7 @@ void change_console(struct vc_data *new_vc)
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* vt to auto control.
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*/
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vc = vc_cons[fg_console].d;
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if (vc->vt_mode.mode == VT_PROCESS) {
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if (vc->vt_mode.mode == VT_PROCESS || vc->vt_mode.mode == VT_PROCESS_AUTO) {
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/*
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* Send the signal as privileged - kill_pid() will
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* tell us if the process has gone or something else
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@ -1693,14 +1693,14 @@ void change_console(struct vc_data *new_vc)
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*/
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vc->vt_newvt = new_vc->vc_num;
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if (kill_pid(vc->vt_pid, vc->vt_mode.relsig, 1) == 0) {
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if(vc->vt_mode.mode == VT_PROCESS)
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/*
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* It worked. Mark the vt to switch to and
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* return. The process needs to send us a
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* VT_RELDISP ioctl to complete the switch.
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*/
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return;
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}
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} else {
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/*
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* The controlling process has died, so we revert back to
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* normal operation. In this case, we'll also change back
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@ -1711,9 +1711,10 @@ void change_console(struct vc_data *new_vc)
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* to account for and tracking tty count may be undesirable.
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*/
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reset_vc(vc);
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}
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/*
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* Fall through to normal (VT_AUTO) handling of the switch...
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* Fall through to normal (VT_AUTO and VT_PROCESS_AUTO) handling of the switch...
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*/
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}
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@ -27,7 +27,7 @@ struct vt_mode {
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#define VT_SETMODE 0x5602 /* set mode of active vt */
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#define VT_AUTO 0x00 /* auto vt switching */
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#define VT_PROCESS 0x01 /* process controls switching */
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#define VT_ACKACQ 0x02 /* acknowledge switch */
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#define VT_PROCESS_AUTO 0x02 /* process is notified of switching */
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struct vt_stat {
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unsigned short v_active; /* active vt */
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@ -38,6 +38,7 @@ struct vt_stat {
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#define VT_SENDSIG 0x5604 /* signal to send to bitmask of vts */
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#define VT_RELDISP 0x5605 /* release display */
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#define VT_ACKACQ 0x02 /* acknowledge switch */
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#define VT_ACTIVATE 0x5606 /* make vt active */
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#define VT_WAITACTIVE 0x5607 /* wait for vt active */
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