git: 049e3fba04e8 - main - vt(4): Skip vt_flush() for nested panics
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Fri, 24 Nov 2023 17:31:55 UTC
The branch main has been updated by dumbbell: URL: https://cgit.FreeBSD.org/src/commit/?id=049e3fba04e82f840cc43080edade0ed415fee72 commit 049e3fba04e82f840cc43080edade0ed415fee72 Author: Jean-Sébastien Pédron <dumbbell@FreeBSD.org> AuthorDate: 2023-11-24 17:30:33 +0000 Commit: Jean-Sébastien Pédron <dumbbell@FreeBSD.org> CommitDate: 2023-11-24 17:31:33 +0000 vt(4): Skip vt_flush() for nested panics [Why] If there is a problem with DRM drivers or in their integration with vt(4) and displaying something on the console triggers a panic, there is a high chance that displaying that panic will trigger another one, recursively. [How] If vt_flush() is called and it detects is is called resursively from another panic, it return immediately, doing nothing, to avoid the risk of triggering another panic. Reviewed by: manu Approved by: manu Differential Revision: https://reviews.freebsd.org/D42056 --- sys/dev/vt/vt_core.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/sys/dev/vt/vt_core.c b/sys/dev/vt/vt_core.c index c97cb80ca3f1..406472a8fbf6 100644 --- a/sys/dev/vt/vt_core.c +++ b/sys/dev/vt/vt_core.c @@ -274,6 +274,8 @@ SYSINIT(vt_update_static, SI_SUB_KMEM, SI_ORDER_ANY, vt_update_static, SYSINIT(vt_early_cons, SI_SUB_INT_CONFIG_HOOKS, SI_ORDER_ANY, vt_upgrade, &vt_consdev); +static bool inside_vt_flush = false; + /* Initialize locks/mem depended members. */ static void vt_update_static(void *dummy) @@ -1344,6 +1346,9 @@ vt_flush(struct vt_device *vd) int cursor_was_shown, cursor_moved; #endif + if (inside_vt_flush && KERNEL_PANICKED()) + return (0); + vw = vd->vd_curwindow; if (vw == NULL) return (0); @@ -1357,6 +1362,8 @@ vt_flush(struct vt_device *vd) vtbuf_lock(&vw->vw_buf); + inside_vt_flush = true; + #ifndef SC_NO_CUTPASTE cursor_was_shown = vd->vd_mshown; cursor_moved = (vd->vd_mx != vd->vd_mx_drawn || @@ -1414,10 +1421,12 @@ vt_flush(struct vt_device *vd) if (tarea.tr_begin.tp_col < tarea.tr_end.tp_col) { vd->vd_driver->vd_bitblt_text(vd, vw, &tarea); + inside_vt_flush = false; vtbuf_unlock(&vw->vw_buf); return (1); } + inside_vt_flush = false; vtbuf_unlock(&vw->vw_buf); return (0); } @@ -1444,6 +1453,9 @@ vtterm_pre_input(struct terminal *tm) { struct vt_window *vw = tm->tm_softc; + if (inside_vt_flush && KERNEL_PANICKED()) + return; + vtbuf_lock(&vw->vw_buf); } @@ -1452,6 +1464,9 @@ vtterm_post_input(struct terminal *tm) { struct vt_window *vw = tm->tm_softc; + if (inside_vt_flush && KERNEL_PANICKED()) + return; + vtbuf_unlock(&vw->vw_buf); vt_resume_flush_timer(vw, 0); }