diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch (renamed from debian/patches-rt/0011-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch) | 46 |
1 files changed, 29 insertions, 17 deletions
diff --git a/debian/patches-rt/0011-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch b/debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch index d6239d704b..0323d580c4 100644 --- a/debian/patches-rt/0011-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch +++ b/debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch @@ -1,27 +1,38 @@ From: John Ogness <john.ogness@linutronix.de> Date: Mon, 18 Mar 2024 10:11:56 +0000 -Subject: [PATCH 11/48] printk: nbcon: Add callbacks to synchronize with driver -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz +Subject: [PATCH 06/46] printk: nbcon: Add callbacks to synchronize with driver +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz Console drivers typically must deal with access to the hardware via user input/output (such as an interactive login shell) and -output of kernel messages via printk() calls. +output of kernel messages via printk() calls. To provide the +necessary synchronization, usually some driver-specific locking +mechanism is used (for example, the port spinlock for uart +serial consoles). -Follow-up commits require that the printk subsystem is able to -synchronize with the driver. Require nbcon consoles to implement -two new callbacks (device_lock(), device_unlock()) that will -use whatever synchronization mechanism the driver is using for -itself (for example, the port lock for uart serial consoles). +Until now, usage of this driver-specific locking has been hidden +from the printk-subsystem and implemented within the various +console callbacks. However, for nbcon consoles, it is necessary +that the printk-subsystem uses the driver-specific locking so +that nbcon console ownership can be acquired _after_ the +driver-specific locking has succeeded. This allows for lock +contention to exist on the more context-friendly driver-specific +locking rather than nbcon console ownership (for non-emergency +and non-panic cases). + +Require nbcon consoles to implement two new callbacks +(device_lock(), device_unlock()) that will use whatever +synchronization mechanism the driver is using for itself. Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- - include/linux/console.h | 42 ++++++++++++++++++++++++++++++++++++++++++ - 1 file changed, 42 insertions(+) + include/linux/console.h | 43 +++++++++++++++++++++++++++++++++++++++++++ + 1 file changed, 43 insertions(+) --- a/include/linux/console.h +++ b/include/linux/console.h -@@ -352,6 +352,48 @@ struct console { +@@ -372,6 +372,49 @@ struct console { */ void (*write_atomic)(struct console *con, struct nbcon_write_context *wctxt); @@ -38,12 +49,13 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> + * use whatever synchronization mechanism the driver is using for + * itself (for example, the port lock for uart serial consoles). + * -+ * This callback is always called from task context. It may use any -+ * synchronization method required by the driver. BUT this callback -+ * MUST also disable migration. The console driver may be using a -+ * synchronization mechanism that already takes care of this (such as -+ * spinlocks). Otherwise this function must explicitly call -+ * migrate_disable(). ++ * The callback is always called from task context. It may use any ++ * synchronization method required by the driver. ++ * ++ * IMPORTANT: The callback MUST disable migration. The console driver ++ * may be using a synchronization mechanism that already takes ++ * care of this (such as spinlocks). Otherwise this function must ++ * explicitly call migrate_disable(). + * + * The flags argument is provided as a convenience to the driver. It + * will be passed again to device_unlock(). It can be ignored if the |