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| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-04-13 00:10:53 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-04-14 21:40:42 -0400 |
| commit | 02413cabd6b67f1444f153ea85d44076deae2056 (patch) | |
| tree | 8d656100a8e523f2f9a5256884f6c868c0ae94df /samples/bpf/offwaketime_kern.c | |
| parent | 074f528eed408b467516e142fa4c45e5b0d2ba16 (diff) | |
| download | lwn-02413cabd6b67f1444f153ea85d44076deae2056.tar.gz lwn-02413cabd6b67f1444f153ea85d44076deae2056.zip | |
bpf, samples: don't zero data when not needed
Remove the zero initialization in the sample programs where appropriate.
Note that this is an optimization which is now possible, old programs
still doing the zero initialization are just fine as well. Also, make
sure we don't have padding issues when we don't memset() the entire
struct anymore.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples/bpf/offwaketime_kern.c')
| -rw-r--r-- | samples/bpf/offwaketime_kern.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/samples/bpf/offwaketime_kern.c b/samples/bpf/offwaketime_kern.c index 983629a31c79..e7d9a0a3d45b 100644 --- a/samples/bpf/offwaketime_kern.c +++ b/samples/bpf/offwaketime_kern.c @@ -11,7 +11,7 @@ #include <linux/version.h> #include <linux/sched.h> -#define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;}) +#define _(P) ({typeof(P) val; bpf_probe_read(&val, sizeof(val), &P); val;}) #define MINBLOCK_US 1 @@ -61,7 +61,7 @@ SEC("kprobe/try_to_wake_up") int waker(struct pt_regs *ctx) { struct task_struct *p = (void *) PT_REGS_PARM1(ctx); - struct wokeby_t woke = {}; + struct wokeby_t woke; u32 pid; pid = _(p->pid); @@ -75,17 +75,19 @@ int waker(struct pt_regs *ctx) static inline int update_counts(void *ctx, u32 pid, u64 delta) { - struct key_t key = {}; struct wokeby_t *woke; u64 zero = 0, *val; + struct key_t key; + __builtin_memset(&key.waker, 0, sizeof(key.waker)); bpf_get_current_comm(&key.target, sizeof(key.target)); key.tret = bpf_get_stackid(ctx, &stackmap, STACKID_FLAGS); + key.wret = 0; woke = bpf_map_lookup_elem(&wokeby, &pid); if (woke) { key.wret = woke->ret; - __builtin_memcpy(&key.waker, woke->name, TASK_COMM_LEN); + __builtin_memcpy(&key.waker, woke->name, sizeof(key.waker)); bpf_map_delete_elem(&wokeby, &pid); } |