[PATCH v4 00/12] Enable lock context analysis

[PATCH v4 00/12] Enable lock context analysis

[Bart Van Assche]

Hi Jens,

During the most recent merge window the following patch series has been merged:
[PATCH v5 00/36] Compiler-Based Context- and Locking-Analysis
(https://lore.kernel.org/lkml/20251219154418.3592607-1-elver@google.com/). That
patch series drops support for verifying lock context annotations with sparse
and introduces support for verifying lock context annotations with Clang. The
support in Clang for lock context annotation and verification is better than
that in sparse. As an example, __cond_acquires() and __guarded_by() are
supported by Clang but not by sparse. Hence this patch series that enables lock
context analysis for the block layer core.

Please consider this patch series for the next merge window.

Thanks,

Bart.

Changes compared to v3:
 - Replaced the "block/bdev: Annotate the blk_holder_ops callback invocations"
   patch with a patch that adds __releases() annotations to the function
   pointers in struct blk_holder_ops.
 - Dropped the blk-zoned patch since a better patch from Christoph has
   been merged.

Changes compared to v2:
 - Retained the block layer core patches and left out the block driver patches.
 - Inlined blkg_conf_open_bdev_frozen() and blkg_conf_close_bdev_frozen().
 - In blkg_conf_open_bdev(), added a return statement if the
   WARN_ON_ONCE() statement triggers.
 - Replaced the "block/ioctl: Add lock context annotations" patch with a
   __release() annotation.
 - Replaced the blk-zoned patch with a patch from Christoph.

Changes compared to v1:
 - Rebased this patch series on top of Jens' for-next branch.
 - Included two patches that split blkg_conf_prep() and blkg_conf_exit().
 - Modified how patches are split. Split the block layer core patch into
   multiple patches and moved the CONTEXT_ANALYSIS := y assignments into the
   block driver patches.
 - Made the new source code comments easier to comprehend.
 - Introduced macros in the mq-deadline and Kyber I/O schedulers to make the
   __acquires() expressions easier to read.
 - Removed the changes from this series that are not block layer changes.

Bart Van Assche (12):
  block: Annotate the queue limits functions
  block/bdev: Annotate the blk_holder_ops callback functions
  block/cgroup: Split blkg_conf_prep()
  block/cgroup: Split blkg_conf_exit()
  block/cgroup: Improve lock context annotations
  block/cgroup: Inline blkg_conf_{open,close}_bdev_frozen()
  block/crypto: Annotate the crypto functions
  block/blk-iocost: Add lock context annotations
  block/blk-mq-debugfs: Improve lock context annotations
  block/kyber: Make the lock context annotations compatible with Clang
  block/mq-deadline: Make the lock context annotations compatible with
    Clang
  block: Enable lock context analysis

 block/Makefile             |  2 +
 block/bfq-cgroup.c         | 11 ++++-
 block/blk-cgroup.c         | 98 ++++++++++----------------------------
 block/blk-cgroup.h         | 13 +++--
 block/blk-crypto-profile.c |  2 +
 block/blk-iocost.c         | 96 +++++++++++++++++++++++--------------
 block/blk-iolatency.c      | 19 ++++----
 block/blk-mq-debugfs.c     | 12 ++---
 block/blk-throttle.c       | 34 +++++++------
 block/blk.h                |  4 ++
 block/kyber-iosched.c      |  7 ++-
 block/mq-deadline.c        | 12 +++--
 include/linux/blkdev.h     | 21 +++++---
 13 files changed, 173 insertions(+), 158 deletions(-)

[PATCH v4 01/12] block: Annotate the queue limits functions

[Bart Van Assche]

Let the thread-safety checker verify whether every start of a queue
limits update is followed by a call to a function that finishes a queue
limits update.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/linux/blkdev.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 890128cdea1c..8651af4fe9d7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1093,15 +1093,17 @@ static inline unsigned int blk_boundary_sectors_left(sector_t offset,
  */
 static inline struct queue_limits
 queue_limits_start_update(struct request_queue *q)
+	__acquires(&q->limits_lock)
 {
 	mutex_lock(&q->limits_lock);
 	return q->limits;
 }
 int queue_limits_commit_update_frozen(struct request_queue *q,
-		struct queue_limits *lim);
+		struct queue_limits *lim) __releases(&q->limits_lock);
 int queue_limits_commit_update(struct request_queue *q,
-		struct queue_limits *lim);
-int queue_limits_set(struct request_queue *q, struct queue_limits *lim);
+		struct queue_limits *lim) __releases(&q->limits_lock);
+int queue_limits_set(struct request_queue *q, struct queue_limits *lim)
+	__must_not_hold(&q->limits_lock);
 int blk_validate_limits(struct queue_limits *lim);
 
 /**
@@ -1113,6 +1115,7 @@ int blk_validate_limits(struct queue_limits *lim);
  * starting update.
  */
 static inline void queue_limits_cancel_update(struct request_queue *q)
+	__releases(&q->limits_lock)
 {
 	mutex_unlock(&q->limits_lock);
 }

[PATCH v4 02/12] block/bdev: Annotate the blk_holder_ops callback functions

[Bart Van Assche]

The four callback functions in blk_holder_ops all release the
bd_holder_lock. Annotate these functions accordingly.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/linux/blkdev.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8651af4fe9d7..d0c181da2da0 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1747,22 +1747,26 @@ void blkdev_show(struct seq_file *seqf, off_t offset);
 #endif
 
 struct blk_holder_ops {
-	void (*mark_dead)(struct block_device *bdev, bool surprise);
+	void (*mark_dead)(struct block_device *bdev, bool surprise)
+		__releases(&bdev->bd_holder_lock);
 
 	/*
 	 * Sync the file system mounted on the block device.
 	 */
-	void (*sync)(struct block_device *bdev);
+	void (*sync)(struct block_device *bdev)
+		__releases(&bdev->bd_holder_lock);
 
 	/*
 	 * Freeze the file system mounted on the block device.
 	 */
-	int (*freeze)(struct block_device *bdev);
+	int (*freeze)(struct block_device *bdev)
+		__releases(&bdev->bd_holder_lock);
 
 	/*
 	 * Thaw the file system mounted on the block device.
 	 */
-	int (*thaw)(struct block_device *bdev);
+	int (*thaw)(struct block_device *bdev)
+		__releases(&bdev->bd_holder_lock);
 };
 
 /*

Re: [PATCH v4 02/12] block/bdev: Annotate the blk_holder_ops callback functions

[Marco Elver]

On Mon, 11 May 2026 at 18:31, Bart Van Assche <bvanassche@acm.org> wrote:
>
> The four callback functions in blk_holder_ops all release the
> bd_holder_lock. Annotate these functions accordingly.
>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Because of this change we'll need clang 23, or you add:

CONTEXT_ANALYSIS := $(call clang-min-version, 230000)

.. although anything else that includes blkdev.h that has
CONTEXT_ANALYSIS := y, but is compiled with clang 22 will break.

Would have been good to wait for clang 23 to be released (August this
year) - although if we consider the next merge window + final release
of Linux 7.2, it might get reasonably close to August.


> ---
>  include/linux/blkdev.h | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 8651af4fe9d7..d0c181da2da0 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1747,22 +1747,26 @@ void blkdev_show(struct seq_file *seqf, off_t offset);
>  #endif
>
>  struct blk_holder_ops {
> -       void (*mark_dead)(struct block_device *bdev, bool surprise);
> +       void (*mark_dead)(struct block_device *bdev, bool surprise)
> +               __releases(&bdev->bd_holder_lock);
>
>         /*
>          * Sync the file system mounted on the block device.
>          */
> -       void (*sync)(struct block_device *bdev);
> +       void (*sync)(struct block_device *bdev)
> +               __releases(&bdev->bd_holder_lock);
>
>         /*
>          * Freeze the file system mounted on the block device.
>          */
> -       int (*freeze)(struct block_device *bdev);
> +       int (*freeze)(struct block_device *bdev)
> +               __releases(&bdev->bd_holder_lock);
>
>         /*
>          * Thaw the file system mounted on the block device.
>          */
> -       int (*thaw)(struct block_device *bdev);
> +       int (*thaw)(struct block_device *bdev)
> +               __releases(&bdev->bd_holder_lock);
>  };
>
>  /*

Re: [PATCH v4 02/12] block/bdev: Annotate the blk_holder_ops callback functions

[Bart Van Assche]

On 5/11/26 3:19 PM, Marco Elver wrote:
> On Mon, 11 May 2026 at 18:31, Bart Van Assche <bvanassche@acm.org> wrote:
>>
>> The four callback functions in blk_holder_ops all release the
>> bd_holder_lock. Annotate these functions accordingly.
>>
>> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> 
> Because of this change we'll need clang 23, or you add:
> 
> CONTEXT_ANALYSIS := $(call clang-min-version, 230000)
> 
> .. although anything else that includes blkdev.h that has
> CONTEXT_ANALYSIS := y, but is compiled with clang 22 will break.
> 
> Would have been good to wait for clang 23 to be released (August this
> year) - although if we consider the next merge window + final release
> of Linux 7.2, it might get reasonably close to August.

Hi Marco,

How about detecting whether or not Clang supports context annotations
for function pointers, e.g. as follows?

diff --git a/init/Kconfig b/init/Kconfig
index 2937c4d308ae..61e592205179 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -32,6 +32,9 @@ config CLANG_VERSION
  	default $(cc-version) if CC_IS_CLANG
  	default 0

+config CC_CONTEXT_ANNOTATIONS_ON_FUNCTION_POINTERS
+	def_bool $(success, echo 'struct __attribute__((capability("m"))) m { 
}; struct a { void (*fp)(struct m* m) 
__attribute__((release_capability(m))); };' | $(CC) -x c - -c -Wall 
-Wextra -Werror -o /dev/null)
+
  config AS_IS_GNU
  	def_bool $(success,test "$(as-name)" = GNU)


Thanks,

Bart.

Re: [PATCH v4 02/12] block/bdev: Annotate the blk_holder_ops callback functions

[Marco Elver]

On Tue, 12 May 2026 at 21:28, Bart Van Assche <bvanassche@acm.org> wrote:
>
> On 5/11/26 3:19 PM, Marco Elver wrote:
> > On Mon, 11 May 2026 at 18:31, Bart Van Assche <bvanassche@acm.org> wrote:
> >>
> >> The four callback functions in blk_holder_ops all release the
> >> bd_holder_lock. Annotate these functions accordingly.
> >>
> >> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> >
> > Because of this change we'll need clang 23, or you add:
> >
> > CONTEXT_ANALYSIS := $(call clang-min-version, 230000)
> >
> > .. although anything else that includes blkdev.h that has
> > CONTEXT_ANALYSIS := y, but is compiled with clang 22 will break.
> >
> > Would have been good to wait for clang 23 to be released (August this
> > year) - although if we consider the next merge window + final release
> > of Linux 7.2, it might get reasonably close to August.
>
> Hi Marco,
>
> How about detecting whether or not Clang supports context annotations
> for function pointers, e.g. as follows?
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 2937c4d308ae..61e592205179 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -32,6 +32,9 @@ config CLANG_VERSION
>         default $(cc-version) if CC_IS_CLANG
>         default 0
>
> +config CC_CONTEXT_ANNOTATIONS_ON_FUNCTION_POINTERS
> +       def_bool $(success, echo 'struct __attribute__((capability("m"))) m {
> }; struct a { void (*fp)(struct m* m)
> __attribute__((release_capability(m))); };' | $(CC) -x c - -c -Wall
> -Wextra -Werror -o /dev/null)
> +
>   config AS_IS_GNU
>         def_bool $(success,test "$(as-name)" = GNU)

That works, but invokes the compiler every time to sync the config,
adding a tiny bit of latency; I think we already have too many of
those, and in this case a version check is sufficient. Clang 23 has
not yet been released, and anyone using the current dev version ought
to use the latest one.

Maybe Nathan can keep me honest about the real overhead of this. :-)

Thanks,
-- Marco

Re: [PATCH v4 02/12] block/bdev: Annotate the blk_holder_ops callback functions

[Nathan Chancellor]

On Wed, May 13, 2026 at 08:54:57AM +0200, Marco Elver wrote:
> On Tue, 12 May 2026 at 21:28, Bart Van Assche <bvanassche@acm.org> wrote:
> >
> > On 5/11/26 3:19 PM, Marco Elver wrote:
> > > On Mon, 11 May 2026 at 18:31, Bart Van Assche <bvanassche@acm.org> wrote:
> > >>
> > >> The four callback functions in blk_holder_ops all release the
> > >> bd_holder_lock. Annotate these functions accordingly.
> > >>
> > >> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> > >
> > > Because of this change we'll need clang 23, or you add:
> > >
> > > CONTEXT_ANALYSIS := $(call clang-min-version, 230000)
> > >
> > > .. although anything else that includes blkdev.h that has
> > > CONTEXT_ANALYSIS := y, but is compiled with clang 22 will break.
> > >
> > > Would have been good to wait for clang 23 to be released (August this
> > > year) - although if we consider the next merge window + final release
> > > of Linux 7.2, it might get reasonably close to August.
> >
> > Hi Marco,
> >
> > How about detecting whether or not Clang supports context annotations
> > for function pointers, e.g. as follows?
> >
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 2937c4d308ae..61e592205179 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -32,6 +32,9 @@ config CLANG_VERSION
> >         default $(cc-version) if CC_IS_CLANG
> >         default 0
> >
> > +config CC_CONTEXT_ANNOTATIONS_ON_FUNCTION_POINTERS
> > +       def_bool $(success, echo 'struct __attribute__((capability("m"))) m {
> > }; struct a { void (*fp)(struct m* m)
> > __attribute__((release_capability(m))); };' | $(CC) -x c - -c -Wall
> > -Wextra -Werror -o /dev/null)
> > +
> >   config AS_IS_GNU
> >         def_bool $(success,test "$(as-name)" = GNU)
> 
> That works, but invokes the compiler every time to sync the config,
> adding a tiny bit of latency; I think we already have too many of
> those, and in this case a version check is sufficient. Clang 23 has
> not yet been released, and anyone using the current dev version ought
> to use the latest one.

Yeah, any time we do a prerelease check, we assume that people are
upgrading their prerelease compilers with regular cadence, otherwise
they are doing something wrong :)

> Maybe Nathan can keep me honest about the real overhead of this. :-)

While doing a dynamic check is more expensive than a version check, I
would not worry much about that overhead if the check is worthwhile or
valuable. In this case, I tend to agree with you that it would just be
better to bump the minimum version of Clang required for context
analysis because of the improvements (other than the function pointer
support) that you have landed in main since release/22.x. While I am
always sad to see support for older compilers dropped, I don't think
clang-22 is widespread enough for that to really matter. On the other
hand, I do worry that if we do not have a wide enough window of
supported compilers for developers / maintainers to use, we won't be
able to uncover potential problems to address in the compiler (I feel
like getting __counted_by deployed was particular painful for this
reason), if that makes sense.

-- 
Cheers,
Nathan

[PATCH v4 03/12] block/cgroup: Split blkg_conf_prep()

[Bart Van Assche]

Move the blkg_conf_open_bdev() call out of blkg_conf_prep() to make it
possible to add lock context annotations to blkg_conf_prep(). Change an
if-statement in blkg_conf_open_bdev() into a WARN_ON_ONCE() call. Export
blkg_conf_open_bdev() because it is called by the BFQ I/O scheduler and
the BFQ I/O scheduler may be built as a kernel module.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/bfq-cgroup.c |  4 ++++
 block/blk-cgroup.c | 18 ++++++++----------
 block/blk-iocost.c |  4 ++++
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index ac83b0668764..38396df9dce7 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1051,6 +1051,10 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
 
 	blkg_conf_init(&ctx, buf);
 
+	ret = blkg_conf_open_bdev(&ctx);
+	if (ret)
+		goto out;
+
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, &ctx);
 	if (ret)
 		goto out;
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 554c87bb4a86..a8d95d51b866 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -771,10 +771,7 @@ EXPORT_SYMBOL_GPL(blkg_conf_init);
  * @ctx->input and get and store the matching bdev in @ctx->bdev. @ctx->body is
  * set to point past the device node prefix.
  *
- * This function may be called multiple times on @ctx and the extra calls become
- * NOOPs. blkg_conf_prep() implicitly calls this function. Use this function
- * explicitly if bdev access is needed without resolving the blkcg / policy part
- * of @ctx->input. Returns -errno on error.
+ * Returns: -errno on error.
  */
 int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 {
@@ -783,8 +780,8 @@ int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 	struct block_device *bdev;
 	int key_len;
 
-	if (ctx->bdev)
-		return 0;
+	if (WARN_ON_ONCE(ctx->bdev))
+		return -EINVAL;
 
 	if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2)
 		return -EINVAL;
@@ -813,6 +810,8 @@ int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 	ctx->bdev = bdev;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(blkg_conf_open_bdev);
+
 /*
  * Similar to blkg_conf_open_bdev, but additionally freezes the queue,
  * ensures the correct locking order between freeze queue and q->rq_qos_mutex.
@@ -857,7 +856,7 @@ unsigned long __must_check blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx)
  * following MAJ:MIN, @ctx->bdev points to the target block device and
  * @ctx->blkg to the blkg being configured.
  *
- * blkg_conf_open_bdev() may be called on @ctx beforehand. On success, this
+ * blkg_conf_open_bdev() must be called on @ctx beforehand. On success, this
  * function returns with queue lock held and must be followed by
  * blkg_conf_exit().
  */
@@ -870,9 +869,8 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 	struct blkcg_gq *blkg;
 	int ret;
 
-	ret = blkg_conf_open_bdev(ctx);
-	if (ret)
-		return ret;
+	if (WARN_ON_ONCE(!ctx->bdev))
+		return -EINVAL;
 
 	disk = ctx->bdev->bd_disk;
 	q = disk->queue;
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 0cca88a366dc..b34f820dedcc 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3140,6 +3140,10 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
 
 	blkg_conf_init(&ctx, buf);
 
+	ret = blkg_conf_open_bdev(&ctx);
+	if (ret)
+		goto err;
+
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, &ctx);
 	if (ret)
 		goto err;

[PATCH v4 04/12] block/cgroup: Split blkg_conf_exit()

[Bart Van Assche]

Split blkg_conf_exit() into blkg_conf_unprep() and blkg_conf_close_bdev()
because blkg_conf_exit() is not compatible with the Clang thread-safety
annotations. Remove blkg_conf_exit(). Rename blkg_conf_exit_frozen() into
blkg_conf_close_bdev_frozen(). Add thread-safety annotations to the new
functions.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/bfq-cgroup.c    |  9 ++++--
 block/blk-cgroup.c    | 57 ++++++++++++++++++------------------
 block/blk-cgroup.h    |  6 ++--
 block/blk-iocost.c    | 67 +++++++++++++++++++++----------------------
 block/blk-iolatency.c | 19 ++++++------
 block/blk-throttle.c  | 34 +++++++++++++---------
 6 files changed, 101 insertions(+), 91 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 38396df9dce7..5d40279d6c9d 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1053,11 +1053,11 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
 
 	ret = blkg_conf_open_bdev(&ctx);
 	if (ret)
-		goto out;
+		return ret;
 
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, &ctx);
 	if (ret)
-		goto out;
+		goto close_bdev;
 
 	if (sscanf(ctx.body, "%llu", &v) == 1) {
 		/* require "default" on dfl */
@@ -1078,8 +1078,11 @@ static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
 		bfq_group_set_weight(bfqg, bfqg->entity.weight, v);
 		ret = 0;
 	}
+
 out:
-	blkg_conf_exit(&ctx);
+	blkg_conf_unprep(&ctx);
+close_bdev:
+	blkg_conf_close_bdev(&ctx);
 	return ret ?: nbytes;
 }
 
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index a8d95d51b866..38d7bcfcbbe8 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -755,7 +755,7 @@ EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
  *
  * Initialize @ctx which can be used to parse blkg config input string @input.
  * Once initialized, @ctx can be used with blkg_conf_open_bdev() and
- * blkg_conf_prep(), and must be cleaned up with blkg_conf_exit().
+ * blkg_conf_prep().
  */
 void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input)
 {
@@ -817,8 +817,8 @@ EXPORT_SYMBOL_GPL(blkg_conf_open_bdev);
  * ensures the correct locking order between freeze queue and q->rq_qos_mutex.
  *
  * This function returns negative error on failure. On success it returns
- * memflags which must be saved and later passed to blkg_conf_exit_frozen
- * for restoring the memalloc scope.
+ * memflags which must be saved and later passed to
+ * blkg_conf_close_bdev_frozen() for restoring the memalloc scope.
  */
 unsigned long __must_check blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx)
 {
@@ -858,7 +858,7 @@ unsigned long __must_check blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx)
  *
  * blkg_conf_open_bdev() must be called on @ctx beforehand. On success, this
  * function returns with queue lock held and must be followed by
- * blkg_conf_exit().
+ * blkg_conf_close_bdev().
  */
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		   struct blkg_conf_ctx *ctx)
@@ -968,42 +968,41 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 EXPORT_SYMBOL_GPL(blkg_conf_prep);
 
 /**
- * blkg_conf_exit - clean up per-blkg config update
+ * blkg_conf_unprep - counterpart of blkg_conf_prep()
  * @ctx: blkg_conf_ctx initialized with blkg_conf_init()
- *
- * Clean up after per-blkg config update. This function must be called on all
- * blkg_conf_ctx's initialized with blkg_conf_init().
  */
-void blkg_conf_exit(struct blkg_conf_ctx *ctx)
-	__releases(&ctx->bdev->bd_queue->queue_lock)
-	__releases(&ctx->bdev->bd_queue->rq_qos_mutex)
+void blkg_conf_unprep(struct blkg_conf_ctx *ctx)
 {
-	if (ctx->blkg) {
-		spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock);
-		ctx->blkg = NULL;
-	}
+	WARN_ON_ONCE(!ctx->blkg);
+	spin_unlock_irq(&ctx->bdev->bd_disk->queue->queue_lock);
+	ctx->blkg = NULL;
+}
+EXPORT_SYMBOL_GPL(blkg_conf_unprep);
 
-	if (ctx->bdev) {
-		mutex_unlock(&ctx->bdev->bd_queue->rq_qos_mutex);
-		blkdev_put_no_open(ctx->bdev);
-		ctx->body = NULL;
-		ctx->bdev = NULL;
-	}
+/**
+ * blkg_conf_close_bdev - counterpart of blkg_conf_open_bdev()
+ * @ctx: blkg_conf_ctx initialized with blkg_conf_init()
+ */
+void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
+{
+	mutex_unlock(&ctx->bdev->bd_queue->rq_qos_mutex);
+	blkdev_put_no_open(ctx->bdev);
+	ctx->body = NULL;
+	ctx->bdev = NULL;
 }
-EXPORT_SYMBOL_GPL(blkg_conf_exit);
+EXPORT_SYMBOL_GPL(blkg_conf_close_bdev);
 
 /*
- * Similar to blkg_conf_exit, but also unfreezes the queue. Should be used
+ * Similar to blkg_close_bdev, but also unfreezes the queue. Should be used
  * when blkg_conf_open_bdev_frozen is used to open the bdev.
  */
-void blkg_conf_exit_frozen(struct blkg_conf_ctx *ctx, unsigned long memflags)
+void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
+				 unsigned long memflags)
 {
-	if (ctx->bdev) {
-		struct request_queue *q = ctx->bdev->bd_queue;
+	struct request_queue *q = ctx->bdev->bd_queue;
 
-		blkg_conf_exit(ctx);
-		blk_mq_unfreeze_queue(q, memflags);
-	}
+	blkg_conf_close_bdev(ctx);
+	blk_mq_unfreeze_queue(q, memflags);
 }
 
 static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src)
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 1cce3294634d..ce90f5b60d52 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -222,8 +222,10 @@ int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
 unsigned long blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx);
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		   struct blkg_conf_ctx *ctx);
-void blkg_conf_exit(struct blkg_conf_ctx *ctx);
-void blkg_conf_exit_frozen(struct blkg_conf_ctx *ctx, unsigned long memflags);
+void blkg_conf_unprep(struct blkg_conf_ctx *ctx);
+void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx);
+void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
+				 unsigned long memflags);
 
 /**
  * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index b34f820dedcc..e611dd63d712 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3142,21 +3142,23 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
 
 	ret = blkg_conf_open_bdev(&ctx);
 	if (ret)
-		goto err;
+		return ret;
 
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, &ctx);
 	if (ret)
-		goto err;
+		goto close_bdev;
 
 	iocg = blkg_to_iocg(ctx.blkg);
 
+	ret = -EINVAL;
+
 	if (!strncmp(ctx.body, "default", 7)) {
 		v = 0;
 	} else {
 		if (!sscanf(ctx.body, "%u", &v))
-			goto einval;
+			goto unprep;
 		if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
-			goto einval;
+			goto unprep;
 	}
 
 	spin_lock(&iocg->ioc->lock);
@@ -3165,14 +3167,15 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
 	weight_updated(iocg, &now);
 	spin_unlock(&iocg->ioc->lock);
 
-	blkg_conf_exit(&ctx);
-	return nbytes;
+	ret = 0;
 
-einval:
-	ret = -EINVAL;
-err:
-	blkg_conf_exit(&ctx);
-	return ret;
+unprep:
+	blkg_conf_unprep(&ctx);
+
+close_bdev:
+	blkg_conf_close_bdev(&ctx);
+
+	return ret ? ret : nbytes;
 }
 
 static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
@@ -3241,10 +3244,8 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 	blkg_conf_init(&ctx, input);
 
 	memflags = blkg_conf_open_bdev_frozen(&ctx);
-	if (IS_ERR_VALUE(memflags)) {
-		ret = memflags;
-		goto err;
-	}
+	if (IS_ERR_VALUE(memflags))
+		return memflags;
 
 	body = ctx.body;
 	disk = ctx.bdev->bd_disk;
@@ -3361,14 +3362,14 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 
 	blk_mq_unquiesce_queue(disk->queue);
 
-	blkg_conf_exit_frozen(&ctx, memflags);
+	blkg_conf_close_bdev_frozen(&ctx, memflags);
 	return nbytes;
 einval:
 	spin_unlock_irq(&ioc->lock);
 	blk_mq_unquiesce_queue(disk->queue);
 	ret = -EINVAL;
 err:
-	blkg_conf_exit_frozen(&ctx, memflags);
+	blkg_conf_close_bdev_frozen(&ctx, memflags);
 	return ret;
 }
 
@@ -3434,20 +3435,20 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
 
 	ret = blkg_conf_open_bdev(&ctx);
 	if (ret)
-		goto err;
+		return ret;
 
 	body = ctx.body;
 	q = bdev_get_queue(ctx.bdev);
 	if (!queue_is_mq(q)) {
 		ret = -EOPNOTSUPP;
-		goto err;
+		goto close_bdev;
 	}
 
 	ioc = q_to_ioc(q);
 	if (!ioc) {
 		ret = blk_iocost_init(ctx.bdev->bd_disk);
 		if (ret)
-			goto err;
+			goto close_bdev;
 		ioc = q_to_ioc(q);
 	}
 
@@ -3458,6 +3459,8 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
 	memcpy(u, ioc->params.i_lcoefs, sizeof(u));
 	user = ioc->user_cost_model;
 
+	ret = -EINVAL;
+
 	while ((p = strsep(&body, " \t\n"))) {
 		substring_t args[MAX_OPT_ARGS];
 		char buf[32];
@@ -3475,20 +3478,20 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
 			else if (!strcmp(buf, "user"))
 				user = true;
 			else
-				goto einval;
+				goto unlock;
 			continue;
 		case COST_MODEL:
 			match_strlcpy(buf, &args[0], sizeof(buf));
 			if (strcmp(buf, "linear"))
-				goto einval;
+				goto unlock;
 			continue;
 		}
 
 		tok = match_token(p, i_lcoef_tokens, args);
 		if (tok == NR_I_LCOEFS)
-			goto einval;
+			goto unlock;
 		if (match_u64(&args[0], &v))
-			goto einval;
+			goto unlock;
 		u[tok] = v;
 		user = true;
 	}
@@ -3500,24 +3503,18 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
 		ioc->user_cost_model = false;
 	}
 	ioc_refresh_params(ioc, true);
-	spin_unlock_irq(&ioc->lock);
 
-	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q, memflags);
-
-	blkg_conf_exit(&ctx);
-	return nbytes;
+	ret = 0;
 
-einval:
+unlock:
 	spin_unlock_irq(&ioc->lock);
 
 	blk_mq_unquiesce_queue(q);
 	blk_mq_unfreeze_queue(q, memflags);
 
-	ret = -EINVAL;
-err:
-	blkg_conf_exit(&ctx);
-	return ret;
+close_bdev:
+	blkg_conf_close_bdev(&ctx);
+	return ret ? ret : nbytes;
 }
 
 static struct cftype ioc_files[] = {
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 53e8dd2dfa8a..1aaee6fb0f59 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -840,7 +840,7 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
 
 	ret = blkg_conf_open_bdev(&ctx);
 	if (ret)
-		goto out;
+		return ret;
 
 	/*
 	 * blk_iolatency_init() may fail after rq_qos_add() succeeds which can
@@ -850,11 +850,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
 	if (!iolat_rq_qos(ctx.bdev->bd_queue))
 		ret = blk_iolatency_init(ctx.bdev->bd_disk);
 	if (ret)
-		goto out;
+		goto close_bdev;
 
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_iolatency, &ctx);
 	if (ret)
-		goto out;
+		goto close_bdev;
 
 	iolat = blkg_to_lat(ctx.blkg);
 	p = ctx.body;
@@ -865,7 +865,7 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
 		char val[21];	/* 18446744073709551616 */
 
 		if (sscanf(tok, "%15[^=]=%20s", key, val) != 2)
-			goto out;
+			goto unprep;
 
 		if (!strcmp(key, "target")) {
 			u64 v;
@@ -875,9 +875,9 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
 			else if (sscanf(val, "%llu", &v) == 1)
 				lat_val = v * NSEC_PER_USEC;
 			else
-				goto out;
+				goto unprep;
 		} else {
-			goto out;
+			goto unprep;
 		}
 	}
 
@@ -889,8 +889,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,
 	if (oldval != iolat->min_lat_nsec)
 		iolatency_clear_scaling(blkg);
 	ret = 0;
-out:
-	blkg_conf_exit(&ctx);
+
+unprep:
+	blkg_conf_unprep(&ctx);
+close_bdev:
+	blkg_conf_close_bdev(&ctx);
 	return ret ?: nbytes;
 }
 
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index cabf91f0d0dc..8f269310cbf4 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1353,21 +1353,21 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
 
 	ret = blkg_conf_open_bdev(&ctx);
 	if (ret)
-		goto out_finish;
+		return ret;
 
 	if (!blk_throtl_activated(ctx.bdev->bd_queue)) {
 		ret = blk_throtl_init(ctx.bdev->bd_disk);
 		if (ret)
-			goto out_finish;
+			goto close_bdev;
 	}
 
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx);
 	if (ret)
-		goto out_finish;
+		goto close_bdev;
 
 	ret = -EINVAL;
 	if (sscanf(ctx.body, "%llu", &v) != 1)
-		goto out_finish;
+		goto unprep;
 	if (!v)
 		v = U64_MAX;
 
@@ -1381,8 +1381,12 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
 
 	tg_conf_updated(tg, false);
 	ret = 0;
-out_finish:
-	blkg_conf_exit(&ctx);
+
+unprep:
+	blkg_conf_unprep(&ctx);
+
+close_bdev:
+	blkg_conf_close_bdev(&ctx);
 	return ret ?: nbytes;
 }
 
@@ -1537,17 +1541,17 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
 
 	ret = blkg_conf_open_bdev(&ctx);
 	if (ret)
-		goto out_finish;
+		return ret;
 
 	if (!blk_throtl_activated(ctx.bdev->bd_queue)) {
 		ret = blk_throtl_init(ctx.bdev->bd_disk);
 		if (ret)
-			goto out_finish;
+			goto close_bdev;
 	}
 
 	ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx);
 	if (ret)
-		goto out_finish;
+		goto close_bdev;
 
 	tg = blkg_to_tg(ctx.blkg);
 	tg_update_carryover(tg);
@@ -1573,11 +1577,11 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
 		p = tok;
 		strsep(&p, "=");
 		if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max")))
-			goto out_finish;
+			goto unprep;
 
 		ret = -ERANGE;
 		if (!val)
-			goto out_finish;
+			goto unprep;
 
 		ret = -EINVAL;
 		if (!strcmp(tok, "rbps"))
@@ -1589,7 +1593,7 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
 		else if (!strcmp(tok, "wiops"))
 			v[3] = min_t(u64, val, UINT_MAX);
 		else
-			goto out_finish;
+			goto unprep;
 	}
 
 	tg->bps[READ] = v[0];
@@ -1599,8 +1603,10 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
 
 	tg_conf_updated(tg, false);
 	ret = 0;
-out_finish:
-	blkg_conf_exit(&ctx);
+unprep:
+	blkg_conf_unprep(&ctx);
+close_bdev:
+	blkg_conf_close_bdev(&ctx);
 	return ret ?: nbytes;
 }
 

[PATCH v4 05/12] block/cgroup: Improve lock context annotations

[Bart Van Assche]

Add lock context annotations where these are missing. Move the
blkg_conf_prep() annotation into block/blk-cgroup.h to make it visible
to all blkg_conf_prep() callers.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-cgroup.c |  1 -
 block/blk-cgroup.h | 15 ++++++++++-----
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 38d7bcfcbbe8..86513c54c217 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -862,7 +862,6 @@ unsigned long __must_check blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx)
  */
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		   struct blkg_conf_ctx *ctx)
-	__acquires(&bdev->bd_queue->queue_lock)
 {
 	struct gendisk *disk;
 	struct request_queue *q;
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index ce90f5b60d52..f0a3af520c55 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -218,14 +218,19 @@ struct blkg_conf_ctx {
 };
 
 void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
-int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
+int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
+	__cond_acquires(0, &ctx->bdev->bd_queue->rq_qos_mutex);
 unsigned long blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx);
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
-		   struct blkg_conf_ctx *ctx);
-void blkg_conf_unprep(struct blkg_conf_ctx *ctx);
-void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx);
+		   struct blkg_conf_ctx *ctx)
+	__cond_acquires(0, &ctx->bdev->bd_disk->queue->queue_lock);
+void blkg_conf_unprep(struct blkg_conf_ctx *ctx)
+	__releases(ctx->bdev->bd_disk->queue->queue_lock);
+void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
+	__releases(&ctx->bdev->bd_queue->rq_qos_mutex);
 void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
-				 unsigned long memflags);
+				 unsigned long memflags)
+	__releases(&ctx->bdev->bd_queue->rq_qos_mutex);
 
 /**
  * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg

[PATCH v4 06/12] block/cgroup: Inline blkg_conf_{open,close}_bdev_frozen()

[Bart Van Assche]

The blkg_conf_open_bdev_frozen() calling convention is not compatible
with lock context annotations. Inline both blkg_conf_open_bdev_frozen()
and blkg_conf_close_bdev_frozen() because these functions only have a
single caller. This patch prepares for enabling lock context analysis.

The type of 'memflags' has been changed from unsigned long into unsigned
int to match the type of current->flags. See also <linux/sched.h>.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-cgroup.c | 46 ----------------------------------------------
 block/blk-cgroup.h |  4 ----
 block/blk-iocost.c | 29 +++++++++++++++++++++++------
 3 files changed, 23 insertions(+), 56 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 86513c54c217..de0f753b8fe5 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -812,39 +812,6 @@ int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 }
 EXPORT_SYMBOL_GPL(blkg_conf_open_bdev);
 
-/*
- * Similar to blkg_conf_open_bdev, but additionally freezes the queue,
- * ensures the correct locking order between freeze queue and q->rq_qos_mutex.
- *
- * This function returns negative error on failure. On success it returns
- * memflags which must be saved and later passed to
- * blkg_conf_close_bdev_frozen() for restoring the memalloc scope.
- */
-unsigned long __must_check blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx)
-{
-	int ret;
-	unsigned long memflags;
-
-	if (ctx->bdev)
-		return -EINVAL;
-
-	ret = blkg_conf_open_bdev(ctx);
-	if (ret < 0)
-		return ret;
-	/*
-	 * At this point, we haven’t started protecting anything related to QoS,
-	 * so we release q->rq_qos_mutex here, which was first acquired in blkg_
-	 * conf_open_bdev. Later, we re-acquire q->rq_qos_mutex after freezing
-	 * the queue to maintain the correct locking order.
-	 */
-	mutex_unlock(&ctx->bdev->bd_queue->rq_qos_mutex);
-
-	memflags = blk_mq_freeze_queue(ctx->bdev->bd_queue);
-	mutex_lock(&ctx->bdev->bd_queue->rq_qos_mutex);
-
-	return memflags;
-}
-
 /**
  * blkg_conf_prep - parse and prepare for per-blkg config update
  * @blkcg: target block cgroup
@@ -991,19 +958,6 @@ void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
 }
 EXPORT_SYMBOL_GPL(blkg_conf_close_bdev);
 
-/*
- * Similar to blkg_close_bdev, but also unfreezes the queue. Should be used
- * when blkg_conf_open_bdev_frozen is used to open the bdev.
- */
-void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
-				 unsigned long memflags)
-{
-	struct request_queue *q = ctx->bdev->bd_queue;
-
-	blkg_conf_close_bdev(ctx);
-	blk_mq_unfreeze_queue(q, memflags);
-}
-
 static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src)
 {
 	int i;
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index f0a3af520c55..f25fecb87c43 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -220,7 +220,6 @@ struct blkg_conf_ctx {
 void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
 int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 	__cond_acquires(0, &ctx->bdev->bd_queue->rq_qos_mutex);
-unsigned long blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx);
 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		   struct blkg_conf_ctx *ctx)
 	__cond_acquires(0, &ctx->bdev->bd_disk->queue->queue_lock);
@@ -228,9 +227,6 @@ void blkg_conf_unprep(struct blkg_conf_ctx *ctx)
 	__releases(ctx->bdev->bd_disk->queue->queue_lock);
 void blkg_conf_close_bdev(struct blkg_conf_ctx *ctx)
 	__releases(&ctx->bdev->bd_queue->rq_qos_mutex);
-void blkg_conf_close_bdev_frozen(struct blkg_conf_ctx *ctx,
-				 unsigned long memflags)
-	__releases(&ctx->bdev->bd_queue->rq_qos_mutex);
 
 /**
  * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index e611dd63d712..353c165c5cd4 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3233,19 +3233,30 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 			     size_t nbytes, loff_t off)
 {
 	struct blkg_conf_ctx ctx;
+	struct request_queue *q;
 	struct gendisk *disk;
 	struct ioc *ioc;
 	u32 qos[NR_QOS_PARAMS];
 	bool enable, user;
 	char *body, *p;
-	unsigned long memflags;
+	unsigned int memflags;
 	int ret;
 
 	blkg_conf_init(&ctx, input);
 
-	memflags = blkg_conf_open_bdev_frozen(&ctx);
-	if (IS_ERR_VALUE(memflags))
-		return memflags;
+	ret = blkg_conf_open_bdev(&ctx);
+	if (ret)
+		return ret;
+	/*
+	 * At this point, we haven’t started protecting anything related to QoS,
+	 * so we release q->rq_qos_mutex here, which was first acquired in blkg_
+	 * conf_open_bdev. Later, we re-acquire q->rq_qos_mutex after freezing
+	 * the queue to maintain the correct locking order.
+	 */
+	mutex_unlock(&ctx.bdev->bd_queue->rq_qos_mutex);
+
+	memflags = blk_mq_freeze_queue(ctx.bdev->bd_queue);
+	mutex_lock(&ctx.bdev->bd_queue->rq_qos_mutex);
 
 	body = ctx.body;
 	disk = ctx.bdev->bd_disk;
@@ -3362,14 +3373,20 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
 
 	blk_mq_unquiesce_queue(disk->queue);
 
-	blkg_conf_close_bdev_frozen(&ctx, memflags);
+	q = ctx.bdev->bd_queue;
+	blkg_conf_close_bdev(&ctx);
+	blk_mq_unfreeze_queue(q, memflags);
+
 	return nbytes;
+
 einval:
 	spin_unlock_irq(&ioc->lock);
 	blk_mq_unquiesce_queue(disk->queue);
 	ret = -EINVAL;
 err:
-	blkg_conf_close_bdev_frozen(&ctx, memflags);
+	q = ctx.bdev->bd_queue;
+	blkg_conf_close_bdev(&ctx);
+	blk_mq_unfreeze_queue(q, memflags);
 	return ret;
 }
 

[PATCH v4 07/12] block/crypto: Annotate the crypto functions

[Bart Van Assche]

Add the lock context annotations required for Clang's thread-safety
analysis.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-crypto-profile.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/blk-crypto-profile.c b/block/blk-crypto-profile.c
index 4ac74443687a..cf447ba4a66e 100644
--- a/block/blk-crypto-profile.c
+++ b/block/blk-crypto-profile.c
@@ -43,6 +43,7 @@ struct blk_crypto_keyslot {
 };
 
 static inline void blk_crypto_hw_enter(struct blk_crypto_profile *profile)
+	__acquires(&profile->lock)
 {
 	/*
 	 * Calling into the driver requires profile->lock held and the device
@@ -55,6 +56,7 @@ static inline void blk_crypto_hw_enter(struct blk_crypto_profile *profile)
 }
 
 static inline void blk_crypto_hw_exit(struct blk_crypto_profile *profile)
+	__releases(&profile->lock)
 {
 	up_write(&profile->lock);
 	if (profile->dev)

[PATCH v4 08/12] block/blk-iocost: Add lock context annotations

[Bart Van Assche]

Since iocg_lock() and iocg_unlock() both use conditional locking,
annotate both with __no_context_analysis and use token_context_lock() to
introduce a new lock context.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-iocost.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 353c165c5cd4..3bb8ce50af42 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -727,7 +727,11 @@ static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio,
 	put_cpu_ptr(gcs);
 }
 
+token_context_lock(ioc_lock);
+
 static void iocg_lock(struct ioc_gq *iocg, bool lock_ioc, unsigned long *flags)
+	__acquires(ioc_lock)
+	__context_unsafe(conditional locking)
 {
 	if (lock_ioc) {
 		spin_lock_irqsave(&iocg->ioc->lock, *flags);
@@ -738,6 +742,8 @@ static void iocg_lock(struct ioc_gq *iocg, bool lock_ioc, unsigned long *flags)
 }
 
 static void iocg_unlock(struct ioc_gq *iocg, bool unlock_ioc, unsigned long *flags)
+	__releases(ioc_lock)
+	__context_unsafe(conditional locking)
 {
 	if (unlock_ioc) {
 		spin_unlock(&iocg->waitq.lock);

[PATCH v4 09/12] block/blk-mq-debugfs: Improve lock context annotations

[Bart Van Assche]

Make the existing lock context annotations compatible with Clang. Add
the lock context annotations that are missing.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-mq-debugfs.c | 12 ++++++------
 block/blk.h            |  4 ++++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 047ec887456b..5c168e82273e 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -20,7 +20,7 @@ static int queue_poll_stat_show(void *data, struct seq_file *m)
 }
 
 static void *queue_requeue_list_start(struct seq_file *m, loff_t *pos)
-	__acquires(&q->requeue_lock)
+	__acquires(&((struct request_queue *)m->private)->requeue_lock)
 {
 	struct request_queue *q = m->private;
 
@@ -36,7 +36,7 @@ static void *queue_requeue_list_next(struct seq_file *m, void *v, loff_t *pos)
 }
 
 static void queue_requeue_list_stop(struct seq_file *m, void *v)
-	__releases(&q->requeue_lock)
+	__releases(&((struct request_queue *)m->private)->requeue_lock)
 {
 	struct request_queue *q = m->private;
 
@@ -298,7 +298,7 @@ int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
 EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);
 
 static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
-	__acquires(&hctx->lock)
+	__acquires(&((struct blk_mq_hw_ctx *)m->private)->lock)
 {
 	struct blk_mq_hw_ctx *hctx = m->private;
 
@@ -314,7 +314,7 @@ static void *hctx_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
 }
 
 static void hctx_dispatch_stop(struct seq_file *m, void *v)
-	__releases(&hctx->lock)
+	__releases(&((struct blk_mq_hw_ctx *)m->private)->lock)
 {
 	struct blk_mq_hw_ctx *hctx = m->private;
 
@@ -486,7 +486,7 @@ static int hctx_dispatch_busy_show(void *data, struct seq_file *m)
 
 #define CTX_RQ_SEQ_OPS(name, type)					\
 static void *ctx_##name##_rq_list_start(struct seq_file *m, loff_t *pos) \
-	__acquires(&ctx->lock)						\
+	__acquires(&((struct blk_mq_ctx *)m->private)->lock)		\
 {									\
 	struct blk_mq_ctx *ctx = m->private;				\
 									\
@@ -503,7 +503,7 @@ static void *ctx_##name##_rq_list_next(struct seq_file *m, void *v,	\
 }									\
 									\
 static void ctx_##name##_rq_list_stop(struct seq_file *m, void *v)	\
-	__releases(&ctx->lock)						\
+	__releases(&((struct blk_mq_ctx *)m->private)->lock)		\
 {									\
 	struct blk_mq_ctx *ctx = m->private;				\
 									\
diff --git a/block/blk.h b/block/blk.h
index b998a7761faf..70b794e89a67 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -754,16 +754,19 @@ static inline void blk_unfreeze_release_lock(struct request_queue *q)
  * reclaim from triggering block I/O.
  */
 static inline void blk_debugfs_lock_nomemsave(struct request_queue *q)
+	__acquires(&q->debugfs_mutex)
 {
 	mutex_lock(&q->debugfs_mutex);
 }
 
 static inline void blk_debugfs_unlock_nomemrestore(struct request_queue *q)
+	__releases(&q->debugfs_mutex)
 {
 	mutex_unlock(&q->debugfs_mutex);
 }
 
 static inline unsigned int __must_check blk_debugfs_lock(struct request_queue *q)
+	__acquires(&q->debugfs_mutex)
 {
 	unsigned int memflags = memalloc_noio_save();
 
@@ -773,6 +776,7 @@ static inline unsigned int __must_check blk_debugfs_lock(struct request_queue *q
 
 static inline void blk_debugfs_unlock(struct request_queue *q,
 				      unsigned int memflags)
+	__releases(&q->debugfs_mutex)
 {
 	blk_debugfs_unlock_nomemrestore(q);
 	memalloc_noio_restore(memflags);

[PATCH v4 10/12] block/kyber: Make the lock context annotations compatible with Clang

[Bart Van Assche]

While sparse ignores the __acquires() and __releases() arguments, Clang
verifies these. Make the arguments of __acquires() and __releases()
acceptable for Clang.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/kyber-iosched.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index b84163d1f851..971818bcdc9d 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -882,6 +882,9 @@ static const struct elv_fs_entry kyber_sched_attrs[] = {
 };
 #undef KYBER_LAT_ATTR
 
+#define HCTX_FROM_SEQ_FILE(m) ((struct blk_mq_hw_ctx *)(m)->private)
+#define KYBER_HCTX_DATA(hctx) ((struct kyber_hctx_data *)(hctx)->sched_data)
+
 #ifdef CONFIG_BLK_DEBUG_FS
 #define KYBER_DEBUGFS_DOMAIN_ATTRS(domain, name)			\
 static int kyber_##name##_tokens_show(void *data, struct seq_file *m)	\
@@ -894,7 +897,7 @@ static int kyber_##name##_tokens_show(void *data, struct seq_file *m)	\
 }									\
 									\
 static void *kyber_##name##_rqs_start(struct seq_file *m, loff_t *pos)	\
-	__acquires(&khd->lock)						\
+	__acquires(&KYBER_HCTX_DATA(HCTX_FROM_SEQ_FILE(m))->lock)	\
 {									\
 	struct blk_mq_hw_ctx *hctx = m->private;			\
 	struct kyber_hctx_data *khd = hctx->sched_data;			\
@@ -913,7 +916,7 @@ static void *kyber_##name##_rqs_next(struct seq_file *m, void *v,	\
 }									\
 									\
 static void kyber_##name##_rqs_stop(struct seq_file *m, void *v)	\
-	__releases(&khd->lock)						\
+	__releases(&KYBER_HCTX_DATA(HCTX_FROM_SEQ_FILE(m))->lock)	\
 {									\
 	struct blk_mq_hw_ctx *hctx = m->private;			\
 	struct kyber_hctx_data *khd = hctx->sched_data;			\

[PATCH v4 11/12] block/mq-deadline: Make the lock context annotations compatible with Clang

[Bart Van Assche]

While sparse ignores the __acquires() and __releases() arguments, Clang
verifies these. Make the arguments of __acquires() and __releases()
acceptable for Clang.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/mq-deadline.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 95917a88976f..824bfc17b2c6 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -794,11 +794,15 @@ static const struct elv_fs_entry deadline_attrs[] = {
 	__ATTR_NULL
 };
 
+#define RQ_FROM_SEQ_FILE(m) ((struct request_queue *)(m)->private)
+#define DD_DATA_FROM_RQ(rq)					\
+	((struct deadline_data *)(rq)->elevator->elevator_data)
+
 #ifdef CONFIG_BLK_DEBUG_FS
 #define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name)		\
 static void *deadline_##name##_fifo_start(struct seq_file *m,		\
 					  loff_t *pos)			\
-	__acquires(&dd->lock)						\
+	__acquires(&DD_DATA_FROM_RQ(RQ_FROM_SEQ_FILE(m))->lock)		\
 {									\
 	struct request_queue *q = m->private;				\
 	struct deadline_data *dd = q->elevator->elevator_data;		\
@@ -819,7 +823,7 @@ static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,	\
 }									\
 									\
 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)	\
-	__releases(&dd->lock)						\
+	__releases(&DD_DATA_FROM_RQ(RQ_FROM_SEQ_FILE(m))->lock)		\
 {									\
 	struct request_queue *q = m->private;				\
 	struct deadline_data *dd = q->elevator->elevator_data;		\
@@ -921,7 +925,7 @@ static int dd_owned_by_driver_show(void *data, struct seq_file *m)
 }
 
 static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
-	__acquires(&dd->lock)
+	__acquires(&DD_DATA_FROM_RQ(RQ_FROM_SEQ_FILE(m))->lock)
 {
 	struct request_queue *q = m->private;
 	struct deadline_data *dd = q->elevator->elevator_data;
@@ -939,7 +943,7 @@ static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
 }
 
 static void deadline_dispatch_stop(struct seq_file *m, void *v)
-	__releases(&dd->lock)
+	__releases(&DD_DATA_FROM_RQ(RQ_FROM_SEQ_FILE(m))->lock)
 {
 	struct request_queue *q = m->private;
 	struct deadline_data *dd = q->elevator->elevator_data;

[PATCH v4 12/12] block: Enable lock context analysis

[Bart Van Assche]

Now that all block/*.c files have been annotated, enable lock context
analysis for all these source files.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/Makefile b/block/Makefile
index 7dce2e44276c..54130faacc21 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -3,6 +3,8 @@
 # Makefile for the kernel block layer
 #
 
+CONTEXT_ANALYSIS := y
+
 obj-y		:= bdev.o fops.o bio.o elevator.o blk-core.o blk-sysfs.o \
 			blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
 			blk-merge.o blk-timeout.o blk-lib.o blk-mq.o \