cxl: Convert to ACQUIRE() for conditional rwsem locking

Use ACQUIRE() to cleanup conditional locking paths in the CXL driver
The ACQUIRE() macro and its associated ACQUIRE_ERR() helpers, like
scoped_cond_guard(), arrange for scoped-based conditional locking. Unlike
scoped_cond_guard(), these macros arrange for an ERR_PTR() to be retrieved
representing the state of the conditional lock.

The goal of this conversion is to complete the removal of all explicit
unlock calls in the subsystem. I.e. the methods to acquire a lock are
solely via guard(), scoped_guard() (for limited cases), or ACQUIRE(). All
unlock is implicit / scope-based. In order to make sure all lock sites are
converted, the existing rwsem's are consolidated and renamed in 'struct
cxl_rwsem'. While that makes the patch noisier it gives a clean cut-off
between old-world (explicit unlock allowed), and new world (explicit unlock
deleted).

Cc: David Lechner <dlechner@baylibre.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Shiju Jose <shiju.jose@huawei.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Shiju Jose <shiju.jose@huawei.com>
Link: https://patch.msgid.link/20250711234932.671292-9-dan.j.williams@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

1 files changed, 18 insertions, 32 deletions

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index f88a13adf7fa..f5fbd34310fd 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -232,15 +232,13 @@ int cxl_trigger_poison_list(struct cxl_memdev *cxlmd)
 	if (!port || !is_cxl_endpoint(port))
 		return -EINVAL;
 
-	rc = down_read_interruptible(&cxl_region_rwsem);
-	if (rc)
+	ACQUIRE(rwsem_read_intr, region_rwsem)(&cxl_rwsem.region);
+	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &region_rwsem)))
 		return rc;
 
-	rc = down_read_interruptible(&cxl_dpa_rwsem);
-	if (rc) {
-		up_read(&cxl_region_rwsem);
+	ACQUIRE(rwsem_read_intr, dpa_rwsem)(&cxl_rwsem.dpa);
+	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &dpa_rwsem)))
 		return rc;
-	}
 
 	if (cxl_num_decoders_committed(port) == 0) {
 		/* No regions mapped to this memdev */
@@ -249,8 +247,6 @@ int cxl_trigger_poison_list(struct cxl_memdev *cxlmd)
 		/* Regions mapped, collect poison by endpoint */
 		rc =  cxl_get_poison_by_endpoint(port);
 	}
-	up_read(&cxl_dpa_rwsem);
-	up_read(&cxl_region_rwsem);
 
 	return rc;
 }
@@ -292,19 +288,17 @@ int cxl_inject_poison(struct cxl_memdev *cxlmd, u64 dpa)
 	if (!IS_ENABLED(CONFIG_DEBUG_FS))
 		return 0;
 
-	rc = down_read_interruptible(&cxl_region_rwsem);
-	if (rc)
+	ACQUIRE(rwsem_read_intr, region_rwsem)(&cxl_rwsem.region);
+	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &region_rwsem)))
 		return rc;
 
-	rc = down_read_interruptible(&cxl_dpa_rwsem);
-	if (rc) {
-		up_read(&cxl_region_rwsem);
+	ACQUIRE(rwsem_read_intr, dpa_rwsem)(&cxl_rwsem.dpa);
+	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &dpa_rwsem)))
 		return rc;
-	}
 
 	rc = cxl_validate_poison_dpa(cxlmd, dpa);
 	if (rc)
-		goto out;
+		return rc;
 
 	inject.address = cpu_to_le64(dpa);
 	mbox_cmd = (struct cxl_mbox_cmd) {
@@ -314,7 +308,7 @@ int cxl_inject_poison(struct cxl_memdev *cxlmd, u64 dpa)
 	};
 	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
 	if (rc)
-		goto out;
+		return rc;
 
 	cxlr = cxl_dpa_to_region(cxlmd, dpa);
 	if (cxlr)
@@ -327,11 +321,8 @@ int cxl_inject_poison(struct cxl_memdev *cxlmd, u64 dpa)
 		.length = cpu_to_le32(1),
 	};
 	trace_cxl_poison(cxlmd, cxlr, &record, 0, 0, CXL_POISON_TRACE_INJECT);
-out:
-	up_read(&cxl_dpa_rwsem);
-	up_read(&cxl_region_rwsem);
 
-	return rc;
+	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_inject_poison, "CXL");
 
@@ -347,19 +338,17 @@ int cxl_clear_poison(struct cxl_memdev *cxlmd, u64 dpa)
 	if (!IS_ENABLED(CONFIG_DEBUG_FS))
 		return 0;
 
-	rc = down_read_interruptible(&cxl_region_rwsem);
-	if (rc)
+	ACQUIRE(rwsem_read_intr, region_rwsem)(&cxl_rwsem.region);
+	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &region_rwsem)))
 		return rc;
 
-	rc = down_read_interruptible(&cxl_dpa_rwsem);
-	if (rc) {
-		up_read(&cxl_region_rwsem);
+	ACQUIRE(rwsem_read_intr, dpa_rwsem)(&cxl_rwsem.dpa);
+	if ((rc = ACQUIRE_ERR(rwsem_read_intr, &dpa_rwsem)))
 		return rc;
-	}
 
 	rc = cxl_validate_poison_dpa(cxlmd, dpa);
 	if (rc)
-		goto out;
+		return rc;
 
 	/*
 	 * In CXL 3.0 Spec 8.2.9.8.4.3, the Clear Poison mailbox command
@@ -378,7 +367,7 @@ int cxl_clear_poison(struct cxl_memdev *cxlmd, u64 dpa)
 
 	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
 	if (rc)
-		goto out;
+		return rc;
 
 	cxlr = cxl_dpa_to_region(cxlmd, dpa);
 	if (cxlr)
@@ -391,11 +380,8 @@ int cxl_clear_poison(struct cxl_memdev *cxlmd, u64 dpa)
 		.length = cpu_to_le32(1),
 	};
 	trace_cxl_poison(cxlmd, cxlr, &record, 0, 0, CXL_POISON_TRACE_CLEAR);
-out:
-	up_read(&cxl_dpa_rwsem);
-	up_read(&cxl_region_rwsem);
 
-	return rc;
+	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_clear_poison, "CXL");