linux-kernel - Re: 174cc7187e6f ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap

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Date:   Tue, 10 Jan 2017 10:41:22 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        "Zheng, Lv" <lv.zheng@...el.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "Moore, Robert" <robert.moore@...el.com>,
        J?rg R?del <joro@...tes.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>
Subject: Re: 174cc7187e6f ACPICA: Tables: Back port
 acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux
 kernel

On Tue, Jan 10, 2017 at 02:27:16AM +0100, Rafael J. Wysocki wrote:
> Well, if the https://patchwork.kernel.org/patch/9504277/ patch from Lv
> worked, the attached one should work too (please test), but it can be
> justified in a slightly more convincing way.

No workie:

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 57fb5f4..acb6118 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -378,7 +378,11 @@ static void acpi_os_drop_map_ref(struct acpi_ioremap *map)
 static void acpi_os_map_cleanup(struct acpi_ioremap *map)
 {
        if (!map->refcount) {
-               synchronize_rcu_expedited();
+               if (acpi_os_initialized) {
+                       pr_err("%s: acpi_os_initialized\n", __func__);
+                       synchronize_rcu_expedited();
+               }
+
                acpi_unmap(map->phys, map->virt);
                kfree(map);
        }

The pr_err() gets issued before the box hangs.

Lv's version which set the bool in acpi_os_map_generic_address() did
work though.

-- 
Regards/Gruss,
    Boris.

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