[1/2] drm/amd/powerplay: smu_v11_0: fix uninitialized variable use

Message ID 20190708140816.1334640-1-arnd@arndb.de
State New
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  • [1/2] drm/amd/powerplay: smu_v11_0: fix uninitialized variable use
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Commit Message

Arnd Bergmann July 8, 2019, 2:07 p.m.
A mistake in the error handling caused an uninitialized
variable to be used:

drivers/gpu/drm/amd/amdgpu/../powerplay/smu_v11_0.c:1102:10: error: variable 'freq' is used uninitialized whenever '?:' condition is false [-Werror,-Wsometimes-uninitialized]
                ret =  smu_get_current_clk_freq_by_table(smu, clk_id, &freq);
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:880:3: note: expanded from macro 'smu_get_current_clk_freq_by_table'
        ((smu)->ppt_funcs->get_current_clk_freq_by_table ? (smu)->ppt_funcs->get_current_clk_freq_by_table((smu), (clk_type), (value)) : 0)
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/smu_v11_0.c:1114:2: note: uninitialized use occurs here
        freq *= 100;
        ^~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/smu_v11_0.c:1102:10: note: remove the '?:' if its condition is always true
                ret =  smu_get_current_clk_freq_by_table(smu, clk_id, &freq);
                       ^
drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:880:3: note: expanded from macro 'smu_get_current_clk_freq_by_table'
        ((smu)->ppt_funcs->get_current_clk_freq_by_table ? (smu)->ppt_funcs->get_current_clk_freq_by_table((smu), (clk_type), (value)) : 0)
         ^
drivers/gpu/drm/amd/amdgpu/../powerplay/smu_v11_0.c:1095:15: note: initialize the variable 'freq' to silence this warning
        uint32_t freq;
                     ^
                      = 0

Bail out of smu_v11_0_get_current_clk_freq() before we get there.

Fixes: e36182490dec ("drm/amd/powerplay: fix dpm freq unit error (10KHz -> Mhz)")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/amd/powerplay/smu_v11_0.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Arnd Bergmann July 8, 2019, 3:58 p.m. | #1
On Mon, Jul 8, 2019 at 5:02 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
> On Mon, Jul 08, 2019 at 04:07:58PM +0200, Arnd Bergmann wrote:
> >       /* if don't has GetDpmClockFreq Message, try get current clock by SmuMetrics_t */
> > -     if (smu_msg_get_index(smu, SMU_MSG_GetDpmClockFreq) == 0)
> > +     if (smu_msg_get_index(smu, SMU_MSG_GetDpmClockFreq) == 0) {
> >               ret =  smu_get_current_clk_freq_by_table(smu, clk_id, &freq);
> > -     else {
> > +             if (ret)
> > +                     return ret;
>
> I am kind of surprised that this fixes the warning. If I am interpreting
> the warning correctly, it is complaining that the member
> get_current_clk_freq_by_table could be NULL and not be called to
> initialize freq and that entire statement will become 0. If that is the
> case, it seems like this added error handling won't fix that problem,
> right?

No, I'm fairly sure this is the right fix. Looking at the whole function:

| static int smu_v11_0_get_current_clk_freq(struct smu_context *smu,
|                                          enum smu_clk_type clk_id,
|                                          uint32_t *value)
|{
|        int ret = 0;
|        uint32_t freq;
|
|        if (clk_id >= SMU_CLK_COUNT || !value)
|                return -EINVAL;
|
|        /* if don't has GetDpmClockFreq Message, try get current
clock by SmuMetrics_t */
|        if (smu_msg_get_index(smu, SMU_MSG_GetDpmClockFreq) == 0) {
|                ret =  smu_get_current_clk_freq_by_table(smu, clk_id, &freq);

Here &freq may or may not get initialized

|        } else {
|                ret = smu_send_smc_msg_with_param(smu, SMU_MSG_GetDpmClockFreq,
|
(smu_clk_get_index(smu, clk_id) << 16));
|                if (ret)
|                        return ret;
|
|               ret = smu_read_smc_arg(smu, &freq);
|                if (ret)
|                        return ret;

Same here, but if it's not initialized, we bail out

|        }
|
|       freq *= 100;
|        *value = freq;

And here it gets assigned to *value

|        return ret;
|}

    Arnd

Patch

diff --git a/drivers/gpu/drm/amd/powerplay/smu_v11_0.c b/drivers/gpu/drm/amd/powerplay/smu_v11_0.c
index c3f9714e9047..bd89a13b6679 100644
--- a/drivers/gpu/drm/amd/powerplay/smu_v11_0.c
+++ b/drivers/gpu/drm/amd/powerplay/smu_v11_0.c
@@ -1099,9 +1099,11 @@  static int smu_v11_0_get_current_clk_freq(struct smu_context *smu,
 		return -EINVAL;
 
 	/* if don't has GetDpmClockFreq Message, try get current clock by SmuMetrics_t */
-	if (smu_msg_get_index(smu, SMU_MSG_GetDpmClockFreq) == 0)
+	if (smu_msg_get_index(smu, SMU_MSG_GetDpmClockFreq) == 0) {
 		ret =  smu_get_current_clk_freq_by_table(smu, clk_id, &freq);
-	else {
+		if (ret)
+			return ret;
+	} else {
 		ret = smu_send_smc_msg_with_param(smu, SMU_MSG_GetDpmClockFreq,
 						  (smu_clk_get_index(smu, clk_id) << 16));
 		if (ret)