MIPS: perf events: handle switch statement falling through warnings

Now that we build with -Wimplicit-fallthrough=3, some warnings are
produced in the arch/mips perf events code that are promoted to errors:

 arch/mips/kernel/perf_event_mipsxx.c:792:3: error: this statement may fall through [-Werror=implicit-fallthrough=]
 arch/mips/kernel/perf_event_mipsxx.c:795:3: error: this statement may fall through [-Werror=implicit-fallthrough=]
 arch/mips/kernel/perf_event_mipsxx.c:798:3: error: this statement may fall through [-Werror=implicit-fallthrough=]
 arch/mips/kernel/perf_event_mipsxx.c:1407:6: error: this statement may fall through [-Werror=implicit-fallthrough=]

Assume the fall throughs are deliberate amd annotate/eliminate them.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Gustavo A. R. Silva <gustavo@embeddedor.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
[paul.burton@mips.com:
  - Make n signed to fix the loop condition.
  - Simplify the initialization of n, which should never have a value
    greater than 4.
  - Invert conditions in the loop to decrease indentation.]
Signed-off-by: Paul Burton <paul.burton@mips.com>

diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c
index d67fb64..f852779 100644 (file)
--- a/arch/mips/kernel/perf_event_mipsxx.c
+++ b/arch/mips/kernel/perf_event_mipsxx.c
@@ -793,15 +793,19 @@ static void reset_counters(void *arg)
        case 4:
                mipsxx_pmu_write_control(3, 0);
                mipspmu.write_counter(3, 0);
+               /* fall through */
        case 3:
                mipsxx_pmu_write_control(2, 0);
                mipspmu.write_counter(2, 0);
+               /* fall through */
        case 2:
                mipsxx_pmu_write_control(1, 0);
                mipspmu.write_counter(1, 0);
+               /* fall through */
        case 1:
                mipsxx_pmu_write_control(0, 0);
                mipspmu.write_counter(0, 0);
+               /* fall through */
        }
 }
 
@@ -1383,7 +1387,7 @@ static int mipsxx_pmu_handle_shared_irq(void)
        struct perf_sample_data data;
        unsigned int counters = mipspmu.num_counters;
        u64 counter;
-       int handled = IRQ_NONE;
+       int n, handled = IRQ_NONE;
        struct pt_regs *regs;
 
        if (cpu_has_perf_cntr_intr_bit && !(read_c0_cause() & CAUSEF_PCI))
@@ -1404,20 +1408,16 @@ static int mipsxx_pmu_handle_shared_irq(void)
 
        perf_sample_data_init(&data, 0, 0);
 
-       switch (counters) {
-#define HANDLE_COUNTER(n)                                              \
-       case n + 1:                                                     \
-               if (test_bit(n, cpuc->used_mask)) {                     \
-                       counter = mipspmu.read_counter(n);              \
-                       if (counter & mipspmu.overflow) {               \
-                               handle_associated_event(cpuc, n, &data, regs); \
-                               handled = IRQ_HANDLED;                  \
-                       }                                               \
-               }
-       HANDLE_COUNTER(3)
-       HANDLE_COUNTER(2)
-       HANDLE_COUNTER(1)
-       HANDLE_COUNTER(0)
+       for (n = counters - 1; n >= 0; n--) {
+               if (!test_bit(n, cpuc->used_mask))
+                       continue;
+
+               counter = mipspmu.read_counter(n);
+               if (!(counter & mipspmu.overflow))
+                       continue;
+
+               handle_associated_event(cpuc, n, &data, regs);
+               handled = IRQ_HANDLED;
        }
 
 #ifdef CONFIG_MIPS_PERF_SHARED_TC_COUNTERS