linux-kernel - [PATCH v2] docs: kernel-hacking: discourage from calling disable

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Message-Id: <20221223112859.937196-1-alexander.sverdlin@siemens.com>
Date:   Fri, 23 Dec 2022 12:28:59 +0100
From:   "A. Sverdlin" <alexander.sverdlin@...mens.com>
To:     linux-doc@...r.kernel.org
Cc:     Alexander Sverdlin <alexander.sverdlin@...mens.com>,
        Jonathan Corbet <corbet@....net>,
        Federico Vaga <federico.vaga@...a.pv.it>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Manfred Spraul <manfred@...orfullife.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] docs: kernel-hacking: discourage from calling disable_irq() in atomic

From: Alexander Sverdlin <alexander.sverdlin@...mens.com>

Correct the example in documentation so that disable_irq() is not being
called in atomic context.

disable_irq() calls sleeping synchronize_irq(), it's not allowed to call
them in atomic context.

Link: https://lore.kernel.org/lkml/87k02wbs2n.ffs@tglx/
Reviewed-by: Manfred Spraul <manfred@...orfullife.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...mens.com>
---
Changelog:
v2: Dropped changes to manage.c because of already applied
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kernel-irq-managec-disable_irq-might-sleep.patch

 Documentation/kernel-hacking/locking.rst                    | 4 ++--
 Documentation/translations/it_IT/kernel-hacking/locking.rst | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/kernel-hacking/locking.rst b/Documentation/kernel-hacking/locking.rst
index 6805ae6e86e65..95fd6e0900d92 100644
--- a/Documentation/kernel-hacking/locking.rst
+++ b/Documentation/kernel-hacking/locking.rst
@@ -1274,11 +1274,11 @@ Manfred Spraul points out that you can still do this, even if the data
 is very occasionally accessed in user context or softirqs/tasklets. The
 irq handler doesn't use a lock, and all other accesses are done as so::
 
-        spin_lock(&lock);
+        mutex_lock(&lock);
         disable_irq(irq);
         ...
         enable_irq(irq);
-        spin_unlock(&lock);
+        mutex_unlock(&lock);
 
 The disable_irq() prevents the irq handler from running
 (and waits for it to finish if it's currently running on other CPUs).
diff --git a/Documentation/translations/it_IT/kernel-hacking/locking.rst b/Documentation/translations/it_IT/kernel-hacking/locking.rst
index 51af37f2d6210..bfbada56cf351 100644
--- a/Documentation/translations/it_IT/kernel-hacking/locking.rst
+++ b/Documentation/translations/it_IT/kernel-hacking/locking.rst
@@ -1309,11 +1309,11 @@ se i dati vengono occasionalmente utilizzati da un contesto utente o
 da un'interruzione software. Il gestore d'interruzione non utilizza alcun
 *lock*, e tutti gli altri accessi verranno fatti così::
 
-        spin_lock(&lock);
+        mutex_lock(&lock);
         disable_irq(irq);
         ...
         enable_irq(irq);
-        spin_unlock(&lock);
+        mutex_unlock(&lock);
 
 La funzione disable_irq() impedisce al gestore d'interruzioni
 d'essere eseguito (e aspetta che finisca nel caso fosse in esecuzione su
-- 
2.34.1