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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-08-07 13:11:37 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-08-07 13:11:37 +0000 |
commit | 85f603d4fd6d85c425502723a17daa94574977de (patch) | |
tree | 188a21432c3b8e8ddb8a08e9a09397164a88181c /debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch | |
parent | Merging upstream version 6.9.7. (diff) | |
download | linux-85f603d4fd6d85c425502723a17daa94574977de.tar.xz linux-85f603d4fd6d85c425502723a17daa94574977de.zip |
Adding debian version 6.9.7-1.debian/6.9.7-1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch')
-rw-r--r-- | debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch b/debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch new file mode 100644 index 0000000000..0323d580c4 --- /dev/null +++ b/debian/patches-rt/0006-printk-nbcon-Add-callbacks-to-synchronize-with-drive.patch @@ -0,0 +1,84 @@ +From: John Ogness <john.ogness@linutronix.de> +Date: Mon, 18 Mar 2024 10:11:56 +0000 +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. To provide the +necessary synchronization, usually some driver-specific locking +mechanism is used (for example, the port spinlock 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 | 43 +++++++++++++++++++++++++++++++++++++++++++ + 1 file changed, 43 insertions(+) + +--- a/include/linux/console.h ++++ b/include/linux/console.h +@@ -372,6 +372,49 @@ struct console { + */ + void (*write_atomic)(struct console *con, struct nbcon_write_context *wctxt); + ++ /** ++ * @device_lock: ++ * ++ * NBCON callback to begin synchronization with driver code. ++ * ++ * 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. This callback is ++ * called by the printk-subsystem whenever it needs to synchronize ++ * with hardware access by the driver. It should be implemented to ++ * use whatever synchronization mechanism the driver is using for ++ * itself (for example, the port lock for uart serial consoles). ++ * ++ * 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 ++ * driver does not need it. ++ */ ++ void (*device_lock)(struct console *con, unsigned long *flags); ++ ++ /** ++ * @device_unlock: ++ * ++ * NBCON callback to finish synchronization with driver code. ++ * ++ * It is the counterpart to device_lock(). ++ * ++ * This callback is always called from task context. It must ++ * appropriately re-enable migration (depending on how device_lock() ++ * disabled migration). ++ * ++ * The flags argument is the value of the same variable that was ++ * passed to device_lock(). ++ */ ++ void (*device_unlock)(struct console *con, unsigned long flags); ++ + atomic_t __private nbcon_state; + atomic_long_t __private nbcon_seq; + struct printk_buffers *pbufs; |