The patch titled
Subject: dax/bus.c: use the right locking mode (read vs write) in size_show
has been added to the -mm mm-unstable branch. Its filename is
dax-busc-use-the-right-locking-mode-read-vs-write-in-size_show.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/dax-busc-use-the-right-locking-mode-read-vs-write-in-size_show.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Subject: dax/bus.c: use the right locking mode (read vs write) in size_show
Date: Tue, 30 Apr 2024 11:44:26 -0600
In size_show(), the dax_dev_rwsem only needs a read lock, but was
acquiring a write lock. Change it to down_read_interruptible() so it
doesn't unnecessarily hold a write lock.
Link: https://lkml.kernel.org/r/20240430-vv-dax_abi_fixes-v3-4-e3dcd755774c@xxxxxxxxx
Fixes: c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local rwsem")
Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Alison Schofield <alison.schofield@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/dax/bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/dax/bus.c~dax-busc-use-the-right-locking-mode-read-vs-write-in-size_show
+++ a/drivers/dax/bus.c
@@ -937,11 +937,11 @@ static ssize_t size_show(struct device *
unsigned long long size;
int rc;
- rc = down_write_killable(&dax_dev_rwsem);
+ rc = down_read_interruptible(&dax_dev_rwsem);
if (rc)
return rc;
size = dev_dax_size(dev_dax);
- up_write(&dax_dev_rwsem);
+ up_read(&dax_dev_rwsem);
return sysfs_emit(buf, "%llu\n", size);
}
_
Patches currently in -mm which might be from vishal.l.verma@xxxxxxxxx are
dax-busc-replace-warn_on_once-with-lockdep-asserts.patch
dax-busc-fix-locking-for-unregister_dax_dev-unregister_dax_mapping-paths.patch
dax-busc-dont-use-down_write_killable-for-non-user-processes.patch
dax-busc-use-the-right-locking-mode-read-vs-write-in-size_show.patch
