[PATCH v2 1/2] cpufreq: acpi-cpufreq: fix P-state index mismatch in extract_io()

[lirongqing <lirongqing@baidu.com>]

From: Li RongQing <lirongqing@baidu.com>

When policy->freq_table is built in acpi_cpufreq_cpu_init(), entries
with duplicate frequencies are skipped. The original P-state index for
each remaining entry is stored in freq_table[].driver_data, so the index
space of freq_table no longer matches perf->states[].

extract_io() walks perf->states[] with index i and uses the same i to
index policy->freq_table[i]. This causes two problems when duplicate
frequencies exist:

  - Returning the frequency of the wrong P-state
  - Returning 0 from a zeroed tail entry, or even CPUFREQ_TABLE_END
    (~1u) reported as 0xfffffffe kHz

Fix it by walking policy->freq_table with cpufreq_for_each_entry() and
using perf->states[pos->driver_data].status, aligning with extract_msr().

Fixes: 8cee1eed8e78 ("cpufreq: ACPI: Remove freq_table from acpi_cpufreq_data")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
 drivers/cpufreq/acpi-cpufreq.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 21639d9..1abe9ab 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -197,14 +197,13 @@ static unsigned extract_io(struct cpufreq_policy *policy, u32 value)
 {
 	struct acpi_cpufreq_data *data = policy->driver_data;
 	struct acpi_processor_performance *perf;
-	int i;
+	struct cpufreq_frequency_table *pos;
 
 	perf = to_perf_data(data);
 
-	for (i = 0; i < perf->state_count; i++) {
-		if (value == perf->states[i].status)
-			return policy->freq_table[i].frequency;
-	}
+	cpufreq_for_each_entry(pos, policy->freq_table)
+		if (value == perf->states[pos->driver_data].status)
+			return pos->frequency;
 	return 0;
 }
 
-- 
2.9.4