[PATCH 0/4] samples/bpf: simple fixes

[PATCH 0/4] samples/bpf: simple fixes

[Taeung Song]

Hello,
This patchset fixes trivial things that I found
when testing 'samples/bpf/' sample code.
I'd appreciate it, if you review this.

Thanks,
Taeung

Taeung Song (4):
  samples/bpf: add missing <linux/if_vlan.h>
  samples/bpf: Check the result of system()
  samples/bpf: Check the error of write() and read()
  samples/bpf: add .gitignore file

 samples/bpf/.gitignore           | 49 ++++++++++++++++++++++++++++++++++++++++
 samples/bpf/parse_varlen.c       |  6 +----
 samples/bpf/test_overhead_user.c | 20 ++++++++++++----
 samples/bpf/trace_event_user.c   | 27 +++++++++++++++++++---
 4 files changed, 89 insertions(+), 13 deletions(-)
 create mode 100644 samples/bpf/.gitignore

-- 
2.7.4

[PATCH 1/4] samples/bpf: add missing <linux/if_vlan.h>

[Taeung Song]

This fixes build error regarding redefinition:

    CLANG-bpf  samples/bpf/parse_varlen.o
  samples/bpf/parse_varlen.c:111:8: error: redefinition of 'vlan_hdr'
  struct vlan_hdr {
         ^
  ./include/linux/if_vlan.h:38:8: note: previous definition is here

So remove duplicate 'struct vlan_hdr' in sample code and include if_vlan.h

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 samples/bpf/parse_varlen.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/samples/bpf/parse_varlen.c b/samples/bpf/parse_varlen.c
index 95c1632..0b6f22f 100644
--- a/samples/bpf/parse_varlen.c
+++ b/samples/bpf/parse_varlen.c
@@ -6,6 +6,7 @@
  */
 #define KBUILD_MODNAME "foo"
 #include <linux/if_ether.h>
+#include <linux/if_vlan.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/in.h>
@@ -108,11 +109,6 @@ static int parse_ipv6(void *data, uint64_t nh_off, void *data_end)
 	return 0;
 }
 
-struct vlan_hdr {
-	uint16_t h_vlan_TCI;
-	uint16_t h_vlan_encapsulated_proto;
-};
-
 SEC("varlen")
 int handle_ingress(struct __sk_buff *skb)
 {
-- 
2.7.4

[PATCH 2/4] samples/bpf: Check the result of system()

[Taeung Song]

To avoid the below build warning message,
use new generate_load() checking the return value.

  ignoring return value of ‘system’, declared with attribute warn_unused_result

And it also refactors the duplicate code of both
test_perf_event_all_cpu() and test_perf_event_task()

Cc: Teng Qin <qinteng@fb.com>
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 samples/bpf/trace_event_user.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
index 1fa1bec..d08046ab8 100644
--- a/samples/bpf/trace_event_user.c
+++ b/samples/bpf/trace_event_user.c
@@ -122,6 +122,16 @@ static void print_stacks(void)
 	}
 }
 
+static inline int generate_load(void)
+{
+	if (system("dd if=/dev/zero of=/dev/null count=5000k status=none") < 0) {
+		printf("failed to generate some load with dd: %s\n", strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
 static void test_perf_event_all_cpu(struct perf_event_attr *attr)
 {
 	int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
@@ -142,7 +152,11 @@ static void test_perf_event_all_cpu(struct perf_event_attr *attr)
 		assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
 		assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE) == 0);
 	}
-	system("dd if=/dev/zero of=/dev/null count=5000k status=none");
+
+	if (generate_load() < 0) {
+		error = 1;
+		goto all_cpu_err;
+	}
 	print_stacks();
 all_cpu_err:
 	for (i--; i >= 0; i--) {
@@ -156,7 +170,7 @@ static void test_perf_event_all_cpu(struct perf_event_attr *attr)
 
 static void test_perf_event_task(struct perf_event_attr *attr)
 {
-	int pmu_fd;
+	int pmu_fd, error = 0;
 
 	/* per task perf event, enable inherit so the "dd ..." command can be traced properly.
 	 * Enabling inherit will cause bpf_perf_prog_read_time helper failure.
@@ -171,10 +185,17 @@ static void test_perf_event_task(struct perf_event_attr *attr)
 	}
 	assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
 	assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE) == 0);
-	system("dd if=/dev/zero of=/dev/null count=5000k status=none");
+
+	if (generate_load() < 0) {
+		error = 1;
+		goto err;
+	}
 	print_stacks();
+err:
 	ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
 	close(pmu_fd);
+	if (error)
+		int_exit(0);
 }
 
 static void test_bpf_perf_event(void)
-- 
2.7.4

[PATCH 3/4] samples/bpf: Check the error of write() and read()

[Taeung Song]

test_task_rename() and test_urandom_read()
can be failed during write() and read(),
So check the result of them.

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 samples/bpf/test_overhead_user.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/samples/bpf/test_overhead_user.c b/samples/bpf/test_overhead_user.c
index 6caf47a..8a88d9c 100644
--- a/samples/bpf/test_overhead_user.c
+++ b/samples/bpf/test_overhead_user.c
@@ -6,6 +6,7 @@
  */
 #define _GNU_SOURCE
 #include <sched.h>
+#include <errno.h>
 #include <stdio.h>
 #include <sys/types.h>
 #include <asm/unistd.h>
@@ -44,8 +45,12 @@ static void test_task_rename(int cpu)
 		exit(1);
 	}
 	start_time = time_get_ns();
-	for (i = 0; i < MAX_CNT; i++)
-		write(fd, buf, sizeof(buf));
+	for (i = 0; i < MAX_CNT; i++) {
+		if (write(fd, buf, sizeof(buf)) < 0) {
+			printf("task rename failed: %s\n", strerror(errno));
+			break;
+		}
+	}
 	printf("task_rename:%d: %lld events per sec\n",
 	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
 	close(fd);
@@ -55,7 +60,7 @@ static void test_urandom_read(int cpu)
 {
 	__u64 start_time;
 	char buf[4];
-	int i, fd;
+	int i, fd, err = 0;
 
 	fd = open("/dev/urandom", O_RDONLY);
 	if (fd < 0) {
@@ -63,8 +68,13 @@ static void test_urandom_read(int cpu)
 		exit(1);
 	}
 	start_time = time_get_ns();
-	for (i = 0; i < MAX_CNT; i++)
-		read(fd, buf, sizeof(buf));
+	for (i = 0; i < MAX_CNT; i++) {
+		err = read(fd, buf, sizeof(buf));
+		if (err < 0 || err >= sizeof(buf)) {
+			printf("failed to read from /dev/urandom: %s\n", strerror(errno));
+			break;
+		}
+	}
 	printf("urandom_read:%d: %lld events per sec\n",
 	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
 	close(fd);
-- 
2.7.4

[PATCH 4/4] samples/bpf: add .gitignore file

[Taeung Song]

For untracked executables of samples/bpf, add this.

  Untracked files:
    (use "git add <file>..." to include in what will be committed)

  	samples/bpf/cpustat
  	samples/bpf/fds_example
  	samples/bpf/lathist
  	samples/bpf/load_sock_ops
	...

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
---
 samples/bpf/.gitignore | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 samples/bpf/.gitignore

diff --git a/samples/bpf/.gitignore b/samples/bpf/.gitignore
new file mode 100644
index 0000000..8ae4940
--- /dev/null
+++ b/samples/bpf/.gitignore
@@ -0,0 +1,49 @@
+cpustat
+fds_example
+lathist
+load_sock_ops
+lwt_len_hist
+map_perf_test
+offwaketime
+per_socket_stats_example
+sampleip
+sock_example
+sockex1
+sockex2
+sockex3
+spintest
+syscall_nrs.h
+syscall_tp
+task_fd_query
+tc_l2_redirect
+test_cgrp2_array_pin
+test_cgrp2_attach
+test_cgrp2_attach2
+test_cgrp2_sock
+test_cgrp2_sock2
+test_current_task_under_cgroup
+test_lru_dist
+test_map_in_map
+test_overhead
+test_probe_write_user
+trace_event
+trace_output
+tracex1
+tracex2
+tracex3
+tracex4
+tracex5
+tracex6
+tracex7
+xdp1
+xdp2
+xdp_adjust_tail
+xdp_fwd
+xdp_monitor
+xdp_redirect
+xdp_redirect_cpu
+xdp_redirect_map
+xdp_router_ipv4
+xdp_rxq_info
+xdp_tx_iptunnel
+xdpsock
-- 
2.7.4

RE: [PATCH 3/4] samples/bpf: Check the error of write() and read()

[David Laight]

From: Taeung Song
> Sent: 02 July 2018 10:15
> test_task_rename() and test_urandom_read()
> can be failed during write() and read(),
> So check the result of them.
> 
> Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
> ---
>  samples/bpf/test_overhead_user.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/samples/bpf/test_overhead_user.c b/samples/bpf/test_overhead_user.c
> index 6caf47a..8a88d9c 100644
> --- a/samples/bpf/test_overhead_user.c
> +++ b/samples/bpf/test_overhead_user.c
> @@ -6,6 +6,7 @@
>   */
>  #define _GNU_SOURCE
>  #include <sched.h>
> +#include <errno.h>
>  #include <stdio.h>
>  #include <sys/types.h>
>  #include <asm/unistd.h>
> @@ -44,8 +45,12 @@ static void test_task_rename(int cpu)
>  		exit(1);
>  	}
>  	start_time = time_get_ns();
> -	for (i = 0; i < MAX_CNT; i++)
> -		write(fd, buf, sizeof(buf));
> +	for (i = 0; i < MAX_CNT; i++) {
> +		if (write(fd, buf, sizeof(buf)) < 0) {
> +			printf("task rename failed: %s\n", strerror(errno));
> +			break;

I'm not sure 'break' generates sensible output.

> +		}
> +	}

What about partial writes??

>  	printf("task_rename:%d: %lld events per sec\n",
>  	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
>  	close(fd);
> @@ -55,7 +60,7 @@ static void test_urandom_read(int cpu)
>  {
>  	__u64 start_time;
>  	char buf[4];
> -	int i, fd;
> +	int i, fd, err = 0;
> 
>  	fd = open("/dev/urandom", O_RDONLY);
>  	if (fd < 0) {
> @@ -63,8 +68,13 @@ static void test_urandom_read(int cpu)
>  		exit(1);
>  	}
>  	start_time = time_get_ns();
> -	for (i = 0; i < MAX_CNT; i++)
> -		read(fd, buf, sizeof(buf));
> +	for (i = 0; i < MAX_CNT; i++) {
> +		err = read(fd, buf, sizeof(buf));
> +		if (err < 0 || err >= sizeof(buf)) {

Overlong reads indicate that something is seriously awry.
Short reads are valid - but maybe not expected.
> +			printf("failed to read from /dev/urandom: %s\n", strerror(errno));


strerror() won't give anything sensible unless err == -1;
You probably want to include the loop count.

> +			break;

The summary print will be gibberish after break.

> +		}
> +	}
>  	printf("urandom_read:%d: %lld events per sec\n",
>  	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
>  	close(fd);
> --
> 2.7.4

Re: [PATCH 3/4] samples/bpf: Check the error of write() and read()

[Taeung Song]

Hi David Laight,

On 07/02/2018 06:25 PM, David Laight wrote:
> From: Taeung Song
>> Sent: 02 July 2018 10:15
>> test_task_rename() and test_urandom_read()
>> can be failed during write() and read(),
>> So check the result of them.
>>
>> Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
>> ---
>>   samples/bpf/test_overhead_user.c | 20 +++++++++++++++-----
>>   1 file changed, 15 insertions(+), 5 deletions(-)
>>
>> diff --git a/samples/bpf/test_overhead_user.c b/samples/bpf/test_overhead_user.c
>> index 6caf47a..8a88d9c 100644
>> --- a/samples/bpf/test_overhead_user.c
>> +++ b/samples/bpf/test_overhead_user.c
>> @@ -6,6 +6,7 @@
>>    */
>>   #define _GNU_SOURCE
>>   #include <sched.h>
>> +#include <errno.h>
>>   #include <stdio.h>
>>   #include <sys/types.h>
>>   #include <asm/unistd.h>
>> @@ -44,8 +45,12 @@ static void test_task_rename(int cpu)
>>   		exit(1);
>>   	}
>>   	start_time = time_get_ns();
>> -	for (i = 0; i < MAX_CNT; i++)
>> -		write(fd, buf, sizeof(buf));
>> +	for (i = 0; i < MAX_CNT; i++) {
>> +		if (write(fd, buf, sizeof(buf)) < 0) {
>> +			printf("task rename failed: %s\n", strerror(errno));
>> +			break;
> 
> I'm not sure 'break' generates sensible output.
> 

OK,
it seems to be better to off on the above error case instead of break;

>> +		}
>> +	}
> 
> What about partial writes??
> 
Hum..
do you mean just skipping several errors of the above write() ?

>>   	printf("task_rename:%d: %lld events per sec\n",
>>   	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
>>   	close(fd);
>> @@ -55,7 +60,7 @@ static void test_urandom_read(int cpu)
>>   {
>>   	__u64 start_time;
>>   	char buf[4];
>> -	int i, fd;
>> +	int i, fd, err = 0;
>>
>>   	fd = open("/dev/urandom", O_RDONLY);
>>   	if (fd < 0) {
>> @@ -63,8 +68,13 @@ static void test_urandom_read(int cpu)
>>   		exit(1);
>>   	}
>>   	start_time = time_get_ns();
>> -	for (i = 0; i < MAX_CNT; i++)
>> -		read(fd, buf, sizeof(buf));
>> +	for (i = 0; i < MAX_CNT; i++) {
>> +		err = read(fd, buf, sizeof(buf));
>> +		if (err < 0 || err >= sizeof(buf)) {
> 
> Overlong reads indicate that something is seriously awry.
> Short reads are valid - but maybe not expected.
>> +			printf("failed to read from /dev/urandom: %s\n", strerror(errno));
> 
> 
> strerror() won't give anything sensible unless err == -1;
> You probably want to include the loop count.
> 
>> +			break;
> 
> The summary print will be gibberish after break.
> 

Ditto, will change the code to do exit(1);
on the err == -1 case.
What do you think about it ?

Thanks,
Taeung

>> +		}
>> +	}
>>   	printf("urandom_read:%d: %lld events per sec\n",
>>   	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
>>   	close(fd);
>> --
>> 2.7.4
>