Messages in this thread Patch in this message | | | From | John Ogness <> | Subject | [PATCH printk v3 7/7] printk: nbcon: Add functions for drivers to mark unsafe regions | Date | Sun, 3 Sep 2023 17:11:39 +0206 |
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From: Thomas Gleixner <tglx@linutronix.de>
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.
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> --- include/linux/console.h | 4 ++++ kernel/printk/nbcon.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+)
diff --git a/include/linux/console.h b/include/linux/console.h index 8d0a309b5286..b3ea9ea66a38 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -459,8 +459,12 @@ static inline bool console_is_registered(const struct console *con) #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; diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c index 1a3df603111d..74f9c33201ae 100644 --- a/kernel/printk/nbcon.c +++ b/kernel/printk/nbcon.c @@ -756,6 +756,46 @@ static bool nbcon_context_update_unsafe(struct nbcon_context *ctxt, bool unsafe) return nbcon_context_can_proceed(ctxt, &cur); } +/** + * 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_update_unsafe(ctxt, true); +} +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_update_unsafe(ctxt, false); +} +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 -- 2.39.2
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