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vt(4): Skip vt_window_switch() for nested panics

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[Why]
The same protection was added to vt_flush() in the previous commit. We
want the same one in vt_window_switch(): if e.g. the DRM driver panics
while handling a call to vt_window_switch(), we don't want to
recursively call vt_window_switch() again and trigger another panic.

Reviewed by:	imp, manu
Approved by:	imp, manu
Differential Revision:	https://reviews.freebsd.org/D42750

(cherry picked from commit 24d6f256f825e5d7f8ca6b5d16499f13614f9cdd)
This commit is contained in:
Jean-Sébastien Pédron 2023-11-24 18:30:33 +01:00 committed by Vladimir Kondratyev
parent 608b148760
commit 95007bfd64
1 changed files with 13 additions and 1 deletions
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14
sys/dev/vt/vt_core.c
View file

@ -275,6 +275,7 @@ SYSINIT(vt_early_cons, SI_SUB_INT_CONFIG_HOOKS, SI_ORDER_ANY, vt_upgrade,
&vt_consdev);
static bool inside_vt_flush = false;
static bool inside_vt_window_switch = false;
/* Initialize locks/mem depended members. */
static void
@ -564,6 +565,11 @@ vt_window_switch(struct vt_window *vw)
struct vt_window *curvw = vd->vd_curwindow;
keyboard_t *kbd;
if (inside_vt_window_switch && KERNEL_PANICKED())
return (0);
inside_vt_window_switch = true;
if (kdb_active) {
/*
* When grabbing the console for the debugger, avoid
@ -575,13 +581,16 @@ vt_window_switch(struct vt_window *vw)
*/
if (curvw == vw)
return (0);
if (!(vw->vw_flags & (VWF_OPENED|VWF_CONSOLE)))
if (!(vw->vw_flags & (VWF_OPENED|VWF_CONSOLE))) {
inside_vt_window_switch = false;
return (EINVAL);
}
vd->vd_curwindow = vw;
vd->vd_flags |= VDF_INVALID;
if (vd->vd_driver->vd_postswitch)
vd->vd_driver->vd_postswitch(vd);
inside_vt_window_switch = false;
return (0);
}
@ -595,10 +604,12 @@ vt_window_switch(struct vt_window *vw)
if ((kdb_active || KERNEL_PANICKED()) &&
vd->vd_driver->vd_postswitch)
vd->vd_driver->vd_postswitch(vd);
inside_vt_window_switch = false;
VT_UNLOCK(vd);
return (0);
}
if (!(vw->vw_flags & (VWF_OPENED|VWF_CONSOLE))) {
inside_vt_window_switch = false;
VT_UNLOCK(vd);
return (EINVAL);
}
@ -627,6 +638,7 @@ vt_window_switch(struct vt_window *vw)
mtx_unlock(&Giant);
DPRINTF(10, "%s(ttyv%d) done\n", __func__, vw->vw_number);
inside_vt_window_switch = false;
return (0);
}