[PATCH 3/4] ACPI: PCC: Free channel on OpRegion deactivation

[Sudeep Holla <sudeep.holla@kernel.org>]

ACPICA calls the address space setup callback with
ACPI_REGION_DEACTIVATE when a PCC OperationRegion is torn down.

The PCC setup callback currently allocates a fresh pcc_data and requests
the mailbox channel before looking at the function argument. If ACPICA
deactivates a region, this can leave the existing region context and
mailbox channel unreleased, and may also request a channel during
teardown.

Handle ACPI_REGION_DEACTIVATE before allocation. Free the PCC mailbox
channel, release the region context and clear the context pointer.

Fixes: 77e2a04745ff ("ACPI: PCC: Implement OperationRegion handler for the PCC Type 3 subtype")
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/acpi/acpi_pcc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c
index 9881c9ee293d..57d13b25c1d6 100644
--- a/drivers/acpi/acpi_pcc.c
+++ b/drivers/acpi/acpi_pcc.c
@@ -55,6 +55,19 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
 	struct pcc_mbox_chan *pcc_chan;
 	acpi_status ret;
 
+	if (function == ACPI_REGION_DEACTIVATE) {
+		data = *region_context;
+		if (data) {
+			pcc_mbox_free_channel(data->pcc_chan);
+			kfree(data);
+			*region_context = NULL;
+		}
+		return AE_OK;
+	}
+
+	if (function != ACPI_REGION_ACTIVATE)
+		return AE_BAD_PARAMETER;
+
 	data = kzalloc_obj(*data);
 	if (!data)
 		return AE_NO_MEMORY;
-- 
2.43.0