From: Dan Williams <[email protected]>

Tighten the CPER protocol error kfifo registration API and symbol
visibility.

Use EXPORT_SYMBOL_FOR_MODULES() instead of EXPORT_SYMBOL_NS_GPL() for
the CPER kfifo registration symbols. This names the consuming module
explicitly and gives compile-time enforcement.

Drop the work_struct argument from the unregister path. Change the
WARN_ONCE condition to a NULL check since there is no caller pointer
to compare against anymore.

Change register/unregister return types to void. Flag double registration
with WARN_ONCE() inside the lock instead of returning an error.

Change cxl_ras_init() to void because there is one consumer and one producer
so the error return was unnecessary. Remove the now-dead error check in
cxl_core_init().

Add a diagnostic log when the driver is not bound in
cxl_cper_handle_prot_err().

Co-developed-by: Terry Bowman <[email protected]>
Signed-off-by: Terry Bowman <[email protected]>
Signed-off-by: Dan Williams <[email protected]>

---

Changes in v17 -> v18:
- New patch.
---
 drivers/acpi/apei/ghes.c | 32 +++++++++++++++-----------------
 drivers/cxl/core/core.h  |  7 ++-----
 drivers/cxl/core/port.c  |  6 +-----
 drivers/cxl/core/ras.c   | 12 +++++++-----
 include/cxl/event.h      | 17 ++++++-----------
 5 files changed, 31 insertions(+), 43 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index ca7a138c1ff2e..187f54e31c33e 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -778,41 +778,41 @@ static void cxl_cper_post_prot_err(struct 
cxl_cper_sec_prot_err *prot_err,
 #endif
 }
 
-int cxl_cper_register_prot_err_work(struct work_struct *work)
+void cxl_cper_register_prot_err_work(struct work_struct *work)
 {
        guard(raw_spinlock_irqsave)(&cxl_cper_prot_err_work_lock);
 
        if (WARN_ONCE(cxl_cper_prot_err_work,
                      "CPER-CXL kfifo consumer already registered\n"))
-               return -EINVAL;
+               return;
        cxl_cper_prot_err_work = work;
-       return 0;
 }
-EXPORT_SYMBOL_NS_GPL(cxl_cper_register_prot_err_work, "CXL");
+EXPORT_SYMBOL_FOR_MODULES(cxl_cper_register_prot_err_work, "cxl_core");
 
-int cxl_cper_unregister_prot_err_work(struct work_struct *work)
+void cxl_cper_unregister_prot_err_work(void)
 {
+       struct work_struct *old;
+
        scoped_guard(raw_spinlock_irqsave, &cxl_cper_prot_err_work_lock) {
-               if (WARN_ONCE(cxl_cper_prot_err_work != work,
-                             "CPER-CXL kfifo consumer mismatch on 
unregister\n"))
-                       return -EINVAL;
+               WARN_ONCE(!cxl_cper_prot_err_work,
+                         "CPER-CXL kfifo consumer not registered on 
unregister\n");
+               old = cxl_cper_prot_err_work;
                cxl_cper_prot_err_work = NULL;
        }
 
-       cancel_work_sync(work);
+       if (old)
+               cancel_work_sync(old);
 
        /* Discard stale entries so they are not replayed on next module load */
        kfifo_reset(&cxl_cper_prot_err_fifo);
-
-       return 0;
 }
-EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_prot_err_work, "CXL");
+EXPORT_SYMBOL_FOR_MODULES(cxl_cper_unregister_prot_err_work, "cxl_core");
 
 int cxl_cper_prot_err_kfifo_get(struct cxl_cper_prot_err_work_data *wd)
 {
        return kfifo_get(&cxl_cper_prot_err_fifo, wd);
 }
-EXPORT_SYMBOL_NS_GPL(cxl_cper_prot_err_kfifo_get, "CXL");
+EXPORT_SYMBOL_FOR_MODULES(cxl_cper_prot_err_kfifo_get, "cxl_core");
 
 /* Room for 8 entries for each of the 4 event log queues */
 #define CXL_CPER_FIFO_DEPTH 32
@@ -867,12 +867,12 @@ int cxl_cper_register_work(struct work_struct *work)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_cper_register_work, "CXL");
 
-int cxl_cper_unregister_work(struct work_struct *work)
+void cxl_cper_unregister_work(struct work_struct *work)
 {
        scoped_guard(raw_spinlock_irqsave, &cxl_cper_work_lock) {
                if (WARN_ONCE(cxl_cper_work != work,
                              "CXL CPER kfifo consumer mismatch on 
unregister\n"))
-                       return -EINVAL;
+                       return;
                cxl_cper_work = NULL;
        }
 
@@ -880,8 +880,6 @@ int cxl_cper_unregister_work(struct work_struct *work)
 
        /* Discard stale entries so they are not replayed on next module load */
        kfifo_reset(&cxl_cper_fifo);
-
-       return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_work, "CXL");
 
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 07555ae638594..23fe40ddf4c6b 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -183,7 +183,7 @@ static inline struct device *dport_to_host(struct cxl_dport 
*dport)
        return &port->dev;
 }
 #ifdef CONFIG_CXL_RAS
-int cxl_ras_init(void);
+void cxl_ras_init(void);
 void cxl_ras_exit(void);
 bool cxl_handle_ras(struct device *dev, void __iomem *ras_base);
 void cxl_handle_cor_ras(struct device *dev, void __iomem *ras_base);
@@ -192,10 +192,7 @@ void cxl_disable_rch_root_ints(struct cxl_dport *dport);
 void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds);
 void devm_cxl_dport_ras_setup(struct cxl_dport *dport);
 #else
-static inline int cxl_ras_init(void)
-{
-       return 0;
-}
+static inline void cxl_ras_init(void) { }
 static inline void cxl_ras_exit(void) { }
 static inline bool cxl_handle_ras(struct device *dev, void __iomem *ras_base)
 {
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 1215ee4f40351..f90f899c31d07 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -2531,14 +2531,10 @@ static __init int cxl_core_init(void)
        if (rc)
                goto err_region;
 
-       rc = cxl_ras_init();
-       if (rc)
-               goto err_ras;
+       cxl_ras_init();
 
        return 0;
 
-err_ras:
-       cxl_region_exit();
 err_region:
        bus_unregister(&cxl_bus_type);
 err_bus:
diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
index 99fb00949c2fa..135f1997e6f4f 100644
--- a/drivers/cxl/core/ras.c
+++ b/drivers/cxl/core/ras.c
@@ -104,8 +104,11 @@ void cxl_cper_handle_prot_err(struct 
cxl_cper_prot_err_work_data *data)
        }
 
        guard(device)(&pdev->dev);
-       if (!pdev->dev.driver)
+       if (!pdev->dev.driver) {
+               dev_warn_ratelimited(&pdev->dev,
+                                    "Device is unbound, abort CPER error 
handling\n");
                return;
+       }
 
        struct device *mem_dev __free(put_device) = bus_find_device(
                &cxl_bus_type, NULL, pdev, match_memdev_by_parent);
@@ -129,15 +132,14 @@ static void cxl_cper_prot_err_work_fn(struct work_struct 
*work)
 }
 static DECLARE_WORK(cxl_cper_prot_err_work, cxl_cper_prot_err_work_fn);
 
-int cxl_ras_init(void)
+void cxl_ras_init(void)
 {
-       return cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
+       cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
 }
 
 void cxl_ras_exit(void)
 {
-       cxl_cper_unregister_prot_err_work(&cxl_cper_prot_err_work);
-       cancel_work_sync(&cxl_cper_prot_err_work);
+       cxl_cper_unregister_prot_err_work();
 }
 
 static void cxl_dport_map_ras(struct cxl_dport *dport)
diff --git a/include/cxl/event.h b/include/cxl/event.h
index ff97fea718d2c..3471d4f75c025 100644
--- a/include/cxl/event.h
+++ b/include/cxl/event.h
@@ -287,10 +287,10 @@ struct cxl_cper_prot_err_work_data {
 
 #ifdef CONFIG_ACPI_APEI_GHES
 int cxl_cper_register_work(struct work_struct *work);
-int cxl_cper_unregister_work(struct work_struct *work);
+void cxl_cper_unregister_work(struct work_struct *work);
 int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd);
-int cxl_cper_register_prot_err_work(struct work_struct *work);
-int cxl_cper_unregister_prot_err_work(struct work_struct *work);
+void cxl_cper_register_prot_err_work(struct work_struct *work);
+void cxl_cper_unregister_prot_err_work(void);
 int cxl_cper_prot_err_kfifo_get(struct cxl_cper_prot_err_work_data *wd);
 #else
 static inline int cxl_cper_register_work(struct work_struct *work)
@@ -298,21 +298,16 @@ static inline int cxl_cper_register_work(struct 
work_struct *work)
        return 0;
 }
 
-static inline int cxl_cper_unregister_work(struct work_struct *work)
-{
-       return 0;
-}
+static inline void cxl_cper_unregister_work(struct work_struct *work) { }
 static inline int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd)
 {
        return 0;
 }
-static inline int cxl_cper_register_prot_err_work(struct work_struct *work)
+static inline void cxl_cper_register_prot_err_work(struct work_struct *work)
 {
-       return 0;
 }
-static inline int cxl_cper_unregister_prot_err_work(struct work_struct *work)
+static inline void cxl_cper_unregister_prot_err_work(void)
 {
-       return 0;
 }
 static inline int cxl_cper_prot_err_kfifo_get(struct 
cxl_cper_prot_err_work_data *wd)
 {
-- 
2.34.1


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