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authorRob Herring (Arm) <robh@kernel.org>2026-08-31 14:43:51 -0500
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2026-09-13 18:17:31 -0700
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treef0b5f37b42fc13b9908a31b657c646b024231cdd /Documentation/block/error-injection.rst
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Input: tsc2007 - read "ti,poll-period" as u32grafted
The "ti,poll-period" property is documented as a normal uint32 cell. The driver used a u64 helper, which makes the helper type disagree with the schema even though the stored value is still small. Read "ti,poll-period" with the u32 helper matching the documented DT cell size. Assisted-by: Codex:gpt-5-5 Signed-off-by: Rob Herring (Arm) <robh@kernel.org> Link: https://patch.msgid.link/20260831194352.1185860-1-robh@kernel.org Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+Configurable Error Injection
+============================
+
+Overview
+--------
+
+Configurable error injection allows injecting specific block layer status codes
+for sector ranges of a block device. Errors can be injected unconditionally, or
+with a given probability.
+
+To use configurable error injection, CONFIG_BLK_ERROR_INJECTION must be enabled.
+
+The only interface is the error_injection debugfs file, which is created for
+each registered gendisk. Writes to this file are used to create or delete rules
+and reads return a list of the current error injection sites.
+
+Options
+-------
+
+The following options specify the operations:
+
+=================== =======================================================
+add add a new rule
+removeall remove all existing rules
+=================== =======================================================
+
+The following options specify the details of the rule for the add operation:
+
+=================== =======================================================
+op=<string> block layer operation this rule applies to. This uses
+ the XYZ for each REQ_OP_XYZ operation, e.g. READ, WRITE
+ or DISCARD. Mandatory.
+status=<string> Status to return. This uses XYZ for each BLK_STS_XYZ
+ code, e.g. IOERR or MEDIUM. Mandatory.
+start=<number> First block layer sector the rule applies to.
+ Optional, defaults to 0.
+nr_sectors=<number> Number of sectors this rule applies.
+ Optional, defaults to the remainder of the device.
+chance=<number> Only return a failure with a likelihood of 1/chance.
+ Optional, defaults to 1 (always).
+=================== =======================================================
+
+Example
+-------
+
+Return BLK_STS_IOERR for one in 10 reads of sector 0 of /dev/nvme0n1:
+
+ $ echo 'add,op=READ,start=0,status=IOERR,chance=10' > /sys/kernel/debug/block/nvme0n1/error_injection
+
+Return BLK_STS_MEDIUM for every write to /dev/nvme0n1:
+
+ $ echo 'add,op=WRITE,start=0,status=MEDIUM' > /sys/kernel/debug/block/nvme0n1/error_injection
+
+Remove all rules for /dev/nvme0n1:
+
+ $ echo 'removeall' > /sys/kernel/debug/block/nvme0n1/error_injection