hwtracing: hisi_ptt: Add support for dynamically updating the filter list

The PCIe devices supported by the PTT trace can be removed/rescanned by
hotplug or through sysfs.  Add support for dynamically updating the
available filter list by registering a PCI bus notifier block. Then user
can always get latest information about available tracing filters and
driver can block the invalid filters of which related devices no longer
exist in the system.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230621092804.15120-3-yangyicong@huawei.com

1 files changed, 40 insertions, 0 deletions

diff --git a/drivers/hwtracing/ptt/hisi_ptt.h b/drivers/hwtracing/ptt/hisi_ptt.h
index 5beb1648c93a..d598411e9cb8 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.h
+++ b/drivers/hwtracing/ptt/hisi_ptt.h
@@ -11,12 +11,15 @@
 
 #include <linux/bits.h>
 #include <linux/cpumask.h>
+#include <linux/kfifo.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/notifier.h>
 #include <linux/pci.h>
 #include <linux/perf_event.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
+#include <linux/workqueue.h>
 
 #define DRV_NAME "hisi_ptt"
 
@@ -71,6 +74,11 @@
 #define HISI_PTT_WAIT_TRACE_TIMEOUT_US	100UL
 #define HISI_PTT_WAIT_POLL_INTERVAL_US	10UL
 
+/* FIFO size for dynamically updating the PTT trace filter list. */
+#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
+/* Delay time for filter updating work */
+#define HISI_PTT_WORK_DELAY_MS			100UL
+
 #define HISI_PCIE_CORE_PORT_ID(devfn)	((PCI_SLOT(devfn) & 0x7) << 1)
 
 /* Definition of the PMU configs */
@@ -135,11 +143,25 @@ struct hisi_ptt_trace_ctrl {
  * struct hisi_ptt_filter_desc - Descriptor of the PTT trace filter
  * @list:    entry of this descriptor in the filter list
  * @is_port: the PCI device of the filter is a Root Port or not
+ * @name:    name of this filter, same as the name of the related PCI device
  * @devid:   the PCI device's devid of the filter
  */
 struct hisi_ptt_filter_desc {
 	struct list_head list;
 	bool is_port;
+	char *name;
+	u16 devid;
+};
+
+/**
+ * struct hisi_ptt_filter_update_info - Information for PTT filter updating
+ * @is_port:    the PCI device to update is a Root Port or not
+ * @is_add:     adding to the filter or not
+ * @devid:      the PCI device's devid of the filter
+ */
+struct hisi_ptt_filter_update_info {
+	bool is_port;
+	bool is_add;
 	u16 devid;
 };
 
@@ -160,6 +182,7 @@ struct hisi_ptt_pmu_buf {
 /**
  * struct hisi_ptt - Per PTT device data
  * @trace_ctrl:   the control information of PTT trace
+ * @hisi_ptt_nb:  dynamic filter update notifier
  * @hotplug_node: node for register cpu hotplug event
  * @hisi_ptt_pmu: the pum device of trace
  * @iobase:       base IO address of the device
@@ -170,10 +193,15 @@ struct hisi_ptt_pmu_buf {
  * @lower_bdf:    the lower BDF range of the PCI devices managed by this PTT device
  * @port_filters: the filter list of root ports
  * @req_filters:  the filter list of requester ID
+ * @filter_lock:  lock to protect the filters
  * @port_mask:    port mask of the managed root ports
+ * @work:         delayed work for filter updating
+ * @filter_update_lock: spinlock to protect the filter update fifo
+ * @filter_update_fifo: fifo of the filters waiting to update the filter list
  */
 struct hisi_ptt {
 	struct hisi_ptt_trace_ctrl trace_ctrl;
+	struct notifier_block hisi_ptt_nb;
 	struct hlist_node hotplug_node;
 	struct pmu hisi_ptt_pmu;
 	void __iomem *iobase;
@@ -192,7 +220,19 @@ struct hisi_ptt {
 	 */
 	struct list_head port_filters;
 	struct list_head req_filters;
+	struct mutex filter_lock;
 	u16 port_mask;
+
+	/*
+	 * We use a delayed work here to avoid indefinitely waiting for
+	 * the hisi_ptt->mutex which protecting the filter list. The
+	 * work will be delayed only if the mutex can not be held,
+	 * otherwise no delay will be applied.
+	 */
+	struct delayed_work work;
+	spinlock_t filter_update_lock;
+	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
+		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
 };
 
 #define to_hisi_ptt(pmu) container_of(pmu, struct hisi_ptt, hisi_ptt_pmu)