diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0082-printk-nbcon-Allow-drivers-to-mark-unsafe-regions-an.patch | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/debian/patches-rt/0082-printk-nbcon-Allow-drivers-to-mark-unsafe-regions-an.patch b/debian/patches-rt/0082-printk-nbcon-Allow-drivers-to-mark-unsafe-regions-an.patch new file mode 100644 index 0000000000..16a07a839e --- /dev/null +++ b/debian/patches-rt/0082-printk-nbcon-Allow-drivers-to-mark-unsafe-regions-an.patch @@ -0,0 +1,136 @@ +From: Thomas Gleixner <tglx@linutronix.de> +Date: Sat, 16 Sep 2023 21:26:07 +0206 +Subject: [PATCH 082/134] printk: nbcon: Allow drivers to mark unsafe regions + and check state +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz + +For the write_atomic callback, the console driver may have unsafe +regions that need to be appropriately marked. Provide functions +that accept the nbcon_write_context struct to allow for the driver +to enter and exit unsafe regions. + +Also provide a function for drivers to check if they are still the +owner of the console. + +Co-developed-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de> +Reviewed-by: Petr Mladek <pmladek@suse.com> +Signed-off-by: Petr Mladek <pmladek@suse.com> +Link: https://lore.kernel.org/r/20230916192007.608398-9-john.ogness@linutronix.de +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + include/linux/console.h | 10 ++++++ + kernel/printk/nbcon.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++ + 2 files changed, 85 insertions(+) + +--- a/include/linux/console.h ++++ b/include/linux/console.h +@@ -451,6 +451,16 @@ static inline bool console_is_registered + lockdep_assert_console_list_lock_held(); \ + hlist_for_each_entry(con, &console_list, node) + ++#ifdef CONFIG_PRINTK ++extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt); ++extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt); ++extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt); ++#else ++static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; } ++static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) { return false; } ++static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; } ++#endif ++ + extern int console_set_on_cmdline; + extern struct console *early_console; + +--- a/kernel/printk/nbcon.c ++++ b/kernel/printk/nbcon.c +@@ -732,6 +732,41 @@ static bool nbcon_context_can_proceed(st + return false; + } + ++/** ++ * nbcon_can_proceed - Check whether ownership can proceed ++ * @wctxt: The write context that was handed to the write function ++ * ++ * Return: True if this context still owns the console. False if ++ * ownership was handed over or taken. ++ * ++ * It is used in nbcon_enter_unsafe() to make sure that it still owns the ++ * lock. Also it is used in nbcon_exit_unsafe() to eventually free the lock ++ * for a higher priority context which asked for the friendly handover. ++ * ++ * It can be called inside an unsafe section when the console is just ++ * temporary in safe state instead of exiting and entering the unsafe state. ++ * ++ * Also it can be called in the safe context before doing an expensive safe ++ * operation. It does not make sense to do the operation when a higher ++ * priority context took the lock. ++ * ++ * When this function returns false then the calling context no longer owns ++ * the console and is no longer allowed to go forward. In this case it must ++ * back out immediately and carefully. The buffer content is also no longer ++ * trusted since it no longer belongs to the calling context. ++ */ ++bool nbcon_can_proceed(struct nbcon_write_context *wctxt) ++{ ++ struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt); ++ struct console *con = ctxt->console; ++ struct nbcon_state cur; ++ ++ nbcon_state_read(con, &cur); ++ ++ return nbcon_context_can_proceed(ctxt, &cur); ++} ++EXPORT_SYMBOL_GPL(nbcon_can_proceed); ++ + #define nbcon_context_enter_unsafe(c) __nbcon_context_update_unsafe(c, true) + #define nbcon_context_exit_unsafe(c) __nbcon_context_update_unsafe(c, false) + +@@ -783,6 +818,46 @@ static bool __nbcon_context_update_unsaf + } + + /** ++ * nbcon_enter_unsafe - Enter an unsafe region in the driver ++ * @wctxt: The write context that was handed to the write function ++ * ++ * Return: True if this context still owns the console. False if ++ * ownership was handed over or taken. ++ * ++ * When this function returns false then the calling context no longer owns ++ * the console and is no longer allowed to go forward. In this case it must ++ * back out immediately and carefully. The buffer content is also no longer ++ * trusted since it no longer belongs to the calling context. ++ */ ++bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) ++{ ++ struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt); ++ ++ return nbcon_context_enter_unsafe(ctxt); ++} ++EXPORT_SYMBOL_GPL(nbcon_enter_unsafe); ++ ++/** ++ * nbcon_exit_unsafe - Exit an unsafe region in the driver ++ * @wctxt: The write context that was handed to the write function ++ * ++ * Return: True if this context still owns the console. False if ++ * ownership was handed over or taken. ++ * ++ * When this function returns false then the calling context no longer owns ++ * the console and is no longer allowed to go forward. In this case it must ++ * back out immediately and carefully. The buffer content is also no longer ++ * trusted since it no longer belongs to the calling context. ++ */ ++bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) ++{ ++ struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt); ++ ++ return nbcon_context_exit_unsafe(ctxt); ++} ++EXPORT_SYMBOL_GPL(nbcon_exit_unsafe); ++ ++/** + * nbcon_emit_next_record - Emit a record in the acquired context + * @wctxt: The write context that will be handed to the write function + * |