[PATCH v1 0/2] amd-pstate-ut: Fix issues observed after loading amd-pstate-ut driver

[PATCH v1 0/2] amd-pstate-ut: Fix issues observed after loading amd-pstate-ut driver

[Swapnil Sapkal]

This series fixes amd-pstate-ut which is currently failing for two
reasons:

1) The code for amd-pstate-ut was written when CONFIG_X86_AMD_PSTATE
was tristate config and amd_pstate can be built as module. In
current implementation the driver is built-in and previous module
parameters are removed. But amd-pstate-ut still try to read old module
parameters. Therefore, test fails. First patch fixes this issue by
removing those module parameter references.

2) In amd_pstate_ut_check_perf() and amd_pstate_ut_check_freq()
functions, cpufreq_cpu_get() is called to get policy of the
cpu and mark it as busy. In these functions cpufreq_cpu_put()
should be used to release the policy. As cpufreq_cpu_put()
is not used to release the policy, any other entity trying to
access the policy is blocked indefinitely. One such scenario
occurs when mode of amd-pstate is changed. Second patch fixes this
by calling cpufreq_cpu_put() wherever necessary.

Swapnil Sapkal (2):
  amd-pstate-ut: Remove module parameter access from amd-pstate-ut
  amd-pstate-ut: Fix kernel panic due to loading amd-pstate-ut driver

 drivers/cpufreq/amd-pstate-ut.c | 46 +++++++++++++--------------------
 1 file changed, 18 insertions(+), 28 deletions(-)

-- 
2.34.1

[PATCH v1 1/2] amd-pstate-ut: Remove module parameter access from amd-pstate-ut

[Swapnil Sapkal]

In amd-pstate-ut, shared memory-based systems call
get_shared_mem() as part of amd_pstate_ut_check_enabled()
function. This function was written when CONFIG_X86_AMD_PSTATE
was tristate config and amd_pstate can be built as a module.
Currently CONFIG_X86_AMD_PSTATE is a boolean config and module
parameter shared_mem is removed. But amd-pstate-ut code still
accesses this module parameter. Remove those accesses.

Fixes: 456ca88d8a52 ("cpufreq: amd-pstate: change amd-pstate driver to be built-in type")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Meng Li <li.meng@amd.com>
Reviewed-by: Wyes Karny <wyes.karny@amd.com>
Suggested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
---
 drivers/cpufreq/amd-pstate-ut.c | 22 ++--------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
index 7f3fe2048981..cf07ee77d3cc 100644
--- a/drivers/cpufreq/amd-pstate-ut.c
+++ b/drivers/cpufreq/amd-pstate-ut.c
@@ -64,27 +64,9 @@ static struct amd_pstate_ut_struct amd_pstate_ut_cases[] = {
 static bool get_shared_mem(void)
 {
 	bool result = false;
-	char path[] = "/sys/module/amd_pstate/parameters/shared_mem";
-	char buf[5] = {0};
-	struct file *filp = NULL;
-	loff_t pos = 0;
-	ssize_t ret;
-
-	if (!boot_cpu_has(X86_FEATURE_CPPC)) {
-		filp = filp_open(path, O_RDONLY, 0);
-		if (IS_ERR(filp))
-			pr_err("%s unable to open %s file!\n", __func__, path);
-		else {
-			ret = kernel_read(filp, &buf, sizeof(buf), &pos);
-			if (ret < 0)
-				pr_err("%s read %s file fail ret=%ld!\n",
-					__func__, path, (long)ret);
-			filp_close(filp, NULL);
-		}
 
-		if ('Y' == *buf)
-			result = true;
-	}
+	if (!boot_cpu_has(X86_FEATURE_CPPC))
+		result = true;
 
 	return result;
 }
-- 
2.34.1

[PATCH v1 2/2] amd-pstate-ut: Fix kernel panic due to loading amd-pstate-ut driver

[Swapnil Sapkal]

After loading amd-pstate-ut driver, amd_pstate_ut_check_perf()
and amd_pstate_ut_check_freq() functions uses cpufreq_cpu_get()
to get the policy of the cpu and mark it as busy. In this
functions cpufreq_cpu_put() should be used to release the
policy. As cpufreq_cpu_put() is not used to release the policy,
any other entity trying to access the policy is blocked indefinitely.
One such scenario is when amd_pstate mode is changed leading to following
splat:

[ 1332.103727] INFO: task bash:2929 blocked for more than 120 seconds.
[ 1332.110001]       Not tainted 6.5.0-rc2-amd-pstate-ut #5
[ 1332.115315] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1332.123140] task:bash            state:D stack:0     pid:2929  ppid:2873   flags:0x00004006
[ 1332.123143] Call Trace:
[ 1332.123145]  <TASK>
[ 1332.123148]  __schedule+0x3c1/0x16a0
[ 1332.123154]  ? _raw_read_lock_irqsave+0x2d/0x70
[ 1332.123157]  schedule+0x6f/0x110
[ 1332.123160]  schedule_timeout+0x14f/0x160
[ 1332.123162]  ? preempt_count_add+0x86/0xd0
[ 1332.123165]  __wait_for_common+0x92/0x190
[ 1332.123168]  ? __pfx_schedule_timeout+0x10/0x10
[ 1332.123170]  wait_for_completion+0x28/0x30
[ 1332.123173]  cpufreq_policy_put_kobj+0x4d/0x90
[ 1332.123177]  cpufreq_policy_free+0x157/0x1d0
[ 1332.123178]  ? preempt_count_add+0x58/0xd0
[ 1332.123180]  cpufreq_remove_dev+0xb6/0x100
[ 1332.123182]  subsys_interface_unregister+0x114/0x120
[ 1332.123185]  ? preempt_count_add+0x58/0xd0
[ 1332.123187]  ? __pfx_amd_pstate_change_driver_mode+0x10/0x10
[ 1332.123190]  cpufreq_unregister_driver+0x3b/0xd0
[ 1332.123192]  amd_pstate_change_driver_mode+0x1e/0x50
[ 1332.123194]  store_status+0xe9/0x180
[ 1332.123197]  dev_attr_store+0x1b/0x30
[ 1332.123199]  sysfs_kf_write+0x42/0x50
[ 1332.123202]  kernfs_fop_write_iter+0x143/0x1d0
[ 1332.123204]  vfs_write+0x2df/0x400
[ 1332.123208]  ksys_write+0x6b/0xf0
[ 1332.123210]  __x64_sys_write+0x1d/0x30
[ 1332.123213]  do_syscall_64+0x60/0x90
[ 1332.123216]  ? fpregs_assert_state_consistent+0x2e/0x50
[ 1332.123219]  ? exit_to_user_mode_prepare+0x49/0x1a0
[ 1332.123223]  ? irqentry_exit_to_user_mode+0xd/0x20
[ 1332.123225]  ? irqentry_exit+0x3f/0x50
[ 1332.123226]  ? exc_page_fault+0x8e/0x190
[ 1332.123228]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 1332.123232] RIP: 0033:0x7fa74c514a37
[ 1332.123234] RSP: 002b:00007ffe31dd0788 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 1332.123238] RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007fa74c514a37
[ 1332.123239] RDX: 0000000000000008 RSI: 000055e27c447aa0 RDI: 0000000000000001
[ 1332.123241] RBP: 000055e27c447aa0 R08: 00007fa74c5d1460 R09: 000000007fffffff
[ 1332.123242] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
[ 1332.123244] R13: 00007fa74c61a780 R14: 00007fa74c616600 R15: 00007fa74c615a00
[ 1332.123247]  </TASK>

Fixed this by calling cpufreq_cpu_put() wherever necessary.

Fixes: 14eb1c96e3a3 ("cpufreq: amd-pstate: Add test module for amd-pstate driver") 
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Meng Li <li.meng@amd.com>
Reviewed-by: Wyes Karny <wyes.karny@amd.com>
Suggested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
---
 drivers/cpufreq/amd-pstate-ut.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
index cf07ee77d3cc..502d494499ae 100644
--- a/drivers/cpufreq/amd-pstate-ut.c
+++ b/drivers/cpufreq/amd-pstate-ut.c
@@ -140,7 +140,7 @@ static void amd_pstate_ut_check_perf(u32 index)
 			if (ret) {
 				amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
 				pr_err("%s cppc_get_perf_caps ret=%d error!\n", __func__, ret);
-				return;
+				goto skip_test;
 			}
 
 			nominal_perf = cppc_perf.nominal_perf;
@@ -151,7 +151,7 @@ static void amd_pstate_ut_check_perf(u32 index)
 			if (ret) {
 				amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
 				pr_err("%s read CPPC_CAP1 ret=%d error!\n", __func__, ret);
-				return;
+				goto skip_test;
 			}
 
 			nominal_perf = AMD_CPPC_NOMINAL_PERF(cap1);
@@ -169,7 +169,7 @@ static void amd_pstate_ut_check_perf(u32 index)
 				nominal_perf, cpudata->nominal_perf,
 				lowest_nonlinear_perf, cpudata->lowest_nonlinear_perf,
 				lowest_perf, cpudata->lowest_perf);
-			return;
+			goto skip_test;
 		}
 
 		if (!((highest_perf >= nominal_perf) &&
@@ -180,11 +180,15 @@ static void amd_pstate_ut_check_perf(u32 index)
 			pr_err("%s cpu%d highest=%d >= nominal=%d > lowest_nonlinear=%d > lowest=%d > 0, the formula is incorrect!\n",
 				__func__, cpu, highest_perf, nominal_perf,
 				lowest_nonlinear_perf, lowest_perf);
-			return;
+			goto skip_test;
 		}
+		cpufreq_cpu_put(policy);
 	}
 
 	amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_PASS;
+	return;
+skip_test:
+	cpufreq_cpu_put(policy);
 }
 
 /*
@@ -212,14 +216,14 @@ static void amd_pstate_ut_check_freq(u32 index)
 			pr_err("%s cpu%d max=%d >= nominal=%d > lowest_nonlinear=%d > min=%d > 0, the formula is incorrect!\n",
 				__func__, cpu, cpudata->max_freq, cpudata->nominal_freq,
 				cpudata->lowest_nonlinear_freq, cpudata->min_freq);
-			return;
+			goto skip_test;
 		}
 
 		if (cpudata->min_freq != policy->min) {
 			amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
 			pr_err("%s cpu%d cpudata_min_freq=%d policy_min=%d, they should be equal!\n",
 				__func__, cpu, cpudata->min_freq, policy->min);
-			return;
+			goto skip_test;
 		}
 
 		if (cpudata->boost_supported) {
@@ -231,16 +235,20 @@ static void amd_pstate_ut_check_freq(u32 index)
 				pr_err("%s cpu%d policy_max=%d should be equal cpu_max=%d or cpu_nominal=%d !\n",
 					__func__, cpu, policy->max, cpudata->max_freq,
 					cpudata->nominal_freq);
-				return;
+				goto skip_test;
 			}
 		} else {
 			amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
 			pr_err("%s cpu%d must support boost!\n", __func__, cpu);
-			return;
+			goto skip_test;
 		}
+		cpufreq_cpu_put(policy);
 	}
 
 	amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_PASS;
+	return;
+skip_test:
+	cpufreq_cpu_put(policy);
 }
 
 static int __init amd_pstate_ut_init(void)
-- 
2.34.1

Re: [PATCH v1 0/2] amd-pstate-ut: Fix issues observed after loading amd-pstate-ut driver

[Rafael J. Wysocki]

On Fri, Aug 18, 2023 at 1:45 PM Swapnil Sapkal <swapnil.sapkal@amd.com> wrote:
>
> This series fixes amd-pstate-ut which is currently failing for two
> reasons:
>
> 1) The code for amd-pstate-ut was written when CONFIG_X86_AMD_PSTATE
> was tristate config and amd_pstate can be built as module. In
> current implementation the driver is built-in and previous module
> parameters are removed. But amd-pstate-ut still try to read old module
> parameters. Therefore, test fails. First patch fixes this issue by
> removing those module parameter references.
>
> 2) In amd_pstate_ut_check_perf() and amd_pstate_ut_check_freq()
> functions, cpufreq_cpu_get() is called to get policy of the
> cpu and mark it as busy. In these functions cpufreq_cpu_put()
> should be used to release the policy. As cpufreq_cpu_put()
> is not used to release the policy, any other entity trying to
> access the policy is blocked indefinitely. One such scenario
> occurs when mode of amd-pstate is changed. Second patch fixes this
> by calling cpufreq_cpu_put() wherever necessary.
>
> Swapnil Sapkal (2):
>   amd-pstate-ut: Remove module parameter access from amd-pstate-ut
>   amd-pstate-ut: Fix kernel panic due to loading amd-pstate-ut driver
>
>  drivers/cpufreq/amd-pstate-ut.c | 46 +++++++++++++--------------------
>  1 file changed, 18 insertions(+), 28 deletions(-)
>
> --

Both patches applied as 6.6 material with subjects adjusted to the
usual cpufreq patch naming pattern and some changelog edits.

Thanks!