patch "coresight: cti: Initialize dynamic sysfs attributes" added to char-misc-linus

This is a note to let you know that I've just added the patch titled

coresight: cti: Initialize dynamic sysfs attributes

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 80624263fa289b3416f7ca309491f1b75e579477 Mon Sep 17 00:00:00 2001
From: Suzuki K Poulose <[email protected]>
Date: Thu, 29 Oct 2020 10:45:58 -0600
Subject: coresight: cti: Initialize dynamic sysfs attributes

With LOCKDEP enabled, CTI driver triggers the following splat due to uninitialized lock class for dynamically allocated attribute objects.

[    5.372901] coresight etm0: CPU0: ETM v4.0 initialized
[    5.376694] coresight etm1: CPU1: ETM v4.0 initialized
[    5.380785] coresight etm2: CPU2: ETM v4.0 initialized
[    5.385851] coresight etm3: CPU3: ETM v4.0 initialized
[    5.389808] BUG: key ffff00000564a798 has not been registered!
[    5.392456] ------------[ cut here ]------------
[    5.398195] DEBUG_LOCKS_WARN_ON(1)
[    5.398233] WARNING: CPU: 1 PID: 32 at kernel/locking/lockdep.c:4623 lockdep_init_map_waits+0x14c/0x260
[    5.406149] Modules linked in:
[    5.415411] CPU: 1 PID: 32 Comm: kworker/1:1 Not tainted 5.9.0-12034-gbbe85027ce80 #51
[    5.418553] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
[    5.426453] Workqueue: events amba_deferred_retry_func
[    5.433299] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--)
[    5.438252] pc : lockdep_init_map_waits+0x14c/0x260
[    5.444410] lr : lockdep_init_map_waits+0x14c/0x260
[    5.449007] sp : ffff800012bbb720

...

[    5.531561] Call trace:
[    5.536847]  lockdep_init_map_waits+0x14c/0x260
[    5.539027]  __kernfs_create_file+0xa8/0x1c8
[    5.543539]  sysfs_add_file_mode_ns+0xd0/0x208
[    5.548054]  internal_create_group+0x118/0x3c8
[    5.552307]  internal_create_groups+0x58/0xb8
[    5.556733]  sysfs_create_groups+0x2c/0x38
[    5.561160]  device_add+0x2d8/0x768
[    5.565148]  device_register+0x28/0x38
[    5.568537]  coresight_register+0xf8/0x320
[    5.572358]  cti_probe+0x1b0/0x3f0

...

Fix this by initializing the attributes when they are allocated.

---
 drivers/hwtracing/coresight/coresight-cti-sysfs.c | 7 +++++++
 1 file changed, 7 insertions(+)

index 392757f3a019..7ff7e7780bbf 100644
@@ -1065,6 +1065,13 @@ static int cti_create_con_sysfs_attr(struct device *dev,
 	}
 	eattr->var = con;
 	con->con_attrs[attr_idx] = &eattr->attr.attr;
+	/*
+	 * Initialize the dynamically allocated attribute
+	 * to avoid LOCKDEP splat. See include/linux/sysfs.h
+	 * for more details.
+	 */
+	sysfs_attr_init(con->con_attrs[attr_idx]);
+
 	return 0;
 }
 

2.29.1