| Message ID | 49d6554536047b9f5526c4ea33990b7c904673d3.1561037262.git.saiprakash.ranjan@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | coresight: Set affinity to invalid for missing CPU phandle | expand |
Sai, Thanks for the patch. Please could you change the subject to : "coresight: Do not default to CPU0 for missing CPU phandle" On 20/06/2019 14:45, Sai Prakash Ranjan wrote: > Affinity defaults to CPU0 in case of missing CPU phandle > and this leads to crashes in some cases because of such > wrong assumption. Fix this by returning -ENODEV in Thats not the right justification. Causing crashes is due to bad DT/firmware. I would be happy with something like : "Coresight platform support assumes that a missing \"cpu\" phandle defaults to CPU0. This could be problematic and unnecessarily binds components to CPU0, where they may not be. Let us make the DT binding rules a bit stricter by not defaulting to CPU0 for missing "cpu" affinity information." Also, you must 1) update the devicetree/bindings document to reflect the same. 2) update the drivers to take appropriate action on the missing CPU where they are expected (e.g, CPU-debug, etm*), to prevent breaking a bisect. > coresight platform for such cases and then handle it > in the coresight drivers. > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> > --- > drivers/hwtracing/coresight/coresight-platform.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c > index 3c5ceda8db24..b1ea60c210e1 100644 > --- a/drivers/hwtracing/coresight/coresight-platform.c > +++ b/drivers/hwtracing/coresight/coresight-platform.c > @@ -160,15 +160,17 @@ static int of_coresight_get_cpu(struct device *dev) > > if (!dev->of_node) > return 0; > + > dn = of_parse_phandle(dev->of_node, "cpu", 0); > - /* Affinity defaults to CPU0 */ > + > + /* Affinity defaults to invalid if no cpu nodes are found*/ The code is self explanatory here. You could drop the comment. > if (!dn) > - return 0; > + return -ENODEV; > + > cpu = of_cpu_node_to_id(dn); > of_node_put(dn); > > - /* Affinity to CPU0 if no cpu nodes are found */ > - return (cpu < 0) ? 0 : cpu; > + return cpu; > } > Suzuki
Hi Suzuki, Thanks for the review. On 6/20/2019 7:25 PM, Suzuki K Poulose wrote: > > Sai, > > Thanks for the patch. Please could you change the subject to : > > "coresight: Do not default to CPU0 for missing CPU phandle" > Sure. > On 20/06/2019 14:45, Sai Prakash Ranjan wrote: >> Affinity defaults to CPU0 in case of missing CPU phandle >> and this leads to crashes in some cases because of such >> wrong assumption. Fix this by returning -ENODEV in > > Thats not the right justification. Causing crashes is due to > bad DT/firmware. I would be happy with something like : > > "Coresight platform support assumes that a missing \"cpu\" phandle > defaults to CPU0. This could be problematic and unnecessarily binds > components to CPU0, where they may not be. Let us make the DT binding > rules a bit stricter by not defaulting to CPU0 for missing "cpu" > affinity information." > > Also, you must > > 1) update the devicetree/bindings document to reflect the same. > 2) update the drivers to take appropriate action on the missing CPU > where they are expected (e.g, CPU-debug, etm*), to prevent > breaking a bisect. > > Sure will do it and repost. >> coresight platform for such cases and then handle it >> in the coresight drivers. >> >> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> >> --- >> drivers/hwtracing/coresight/coresight-platform.c | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-platform.c >> b/drivers/hwtracing/coresight/coresight-platform.c >> index 3c5ceda8db24..b1ea60c210e1 100644 >> --- a/drivers/hwtracing/coresight/coresight-platform.c >> +++ b/drivers/hwtracing/coresight/coresight-platform.c >> @@ -160,15 +160,17 @@ static int of_coresight_get_cpu(struct device *dev) >> if (!dev->of_node) >> return 0; >> + >> dn = of_parse_phandle(dev->of_node, "cpu", 0); >> - /* Affinity defaults to CPU0 */ >> + >> + /* Affinity defaults to invalid if no cpu nodes are found*/ > > The code is self explanatory here. You could drop the comment. > Sure. >> if (!dn) >> - return 0; >> + return -ENODEV; >> + >> cpu = of_cpu_node_to_id(dn); >> of_node_put(dn); >> - /* Affinity to CPU0 if no cpu nodes are found */ >> - return (cpu < 0) ? 0 : cpu; >> + return cpu; >> } > > Suzuki -Sai
Hi Sai, On Thu, Jun 20, 2019 at 07:15:46PM +0530, Sai Prakash Ranjan wrote: > Affinity defaults to CPU0 in case of missing CPU phandle > and this leads to crashes in some cases because of such > wrong assumption. Fix this by returning -ENODEV in > coresight platform for such cases and then handle it > in the coresight drivers. > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> > --- > drivers/hwtracing/coresight/coresight-platform.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c > index 3c5ceda8db24..b1ea60c210e1 100644 > --- a/drivers/hwtracing/coresight/coresight-platform.c > +++ b/drivers/hwtracing/coresight/coresight-platform.c > @@ -160,15 +160,17 @@ static int of_coresight_get_cpu(struct device *dev) > > if (!dev->of_node) > return 0; An error should be returned if the above condition is true. > + Spurious newline > dn = of_parse_phandle(dev->of_node, "cpu", 0); > - /* Affinity defaults to CPU0 */ > + > + /* Affinity defaults to invalid if no cpu nodes are found*/ > if (!dn) > - return 0; > + return -ENODEV; > + > cpu = of_cpu_node_to_id(dn); > of_node_put(dn); > > - /* Affinity to CPU0 if no cpu nodes are found */ > - return (cpu < 0) ? 0 : cpu; > + return cpu; > } > > /* > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member > of Code Aurora Forum, hosted by The Linux Foundation >
Hi Mathieu, Thanks for the review comments. On 6/20/2019 11:09 PM, Mathieu Poirier wrote: > Hi Sai, > > On Thu, Jun 20, 2019 at 07:15:46PM +0530, Sai Prakash Ranjan wrote: >> Affinity defaults to CPU0 in case of missing CPU phandle >> and this leads to crashes in some cases because of such >> wrong assumption. Fix this by returning -ENODEV in >> coresight platform for such cases and then handle it >> in the coresight drivers. >> >> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> >> --- >> drivers/hwtracing/coresight/coresight-platform.c | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c >> index 3c5ceda8db24..b1ea60c210e1 100644 >> --- a/drivers/hwtracing/coresight/coresight-platform.c >> +++ b/drivers/hwtracing/coresight/coresight-platform.c >> @@ -160,15 +160,17 @@ static int of_coresight_get_cpu(struct device *dev) >> >> if (!dev->of_node) >> return 0; > > An error should be returned if the above condition is true. > Will do it, thanks. >> + > > Spurious newline > This was on purpose, the code looks much cleaner. -Sai
diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c index 3c5ceda8db24..b1ea60c210e1 100644 --- a/drivers/hwtracing/coresight/coresight-platform.c +++ b/drivers/hwtracing/coresight/coresight-platform.c @@ -160,15 +160,17 @@ static int of_coresight_get_cpu(struct device *dev) if (!dev->of_node) return 0; + dn = of_parse_phandle(dev->of_node, "cpu", 0); - /* Affinity defaults to CPU0 */ + + /* Affinity defaults to invalid if no cpu nodes are found*/ if (!dn) - return 0; + return -ENODEV; + cpu = of_cpu_node_to_id(dn); of_node_put(dn); - /* Affinity to CPU0 if no cpu nodes are found */ - return (cpu < 0) ? 0 : cpu; + return cpu; } /*
Affinity defaults to CPU0 in case of missing CPU phandle and this leads to crashes in some cases because of such wrong assumption. Fix this by returning -ENODEV in coresight platform for such cases and then handle it in the coresight drivers. Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> --- drivers/hwtracing/coresight/coresight-platform.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)