hw-breakpoints: Simplify error handling in breakpoint creation requests

This simplifies the error handling when we create a breakpoint.
We don't need to check the NULL return value corner case anymore
since we have improved perf_event_create_kernel_counter() to
always return an error code in the failure case.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1259210142-5714-3-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index b25f894..75e0cd8 100644 (file)
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -657,10 +657,7 @@ restore:
                                               tsk, true);
                thread->ptrace_bps[i] = NULL;
 
-               if (!bp) { /* incorrect bp, or we have a bug in bp API */
-                       rc = -EINVAL;
-                       break;
-               }
+               /* Incorrect bp, or we have a bug in bp API */
                if (IS_ERR(bp)) {
                        rc = PTR_ERR(bp);
                        bp = NULL;
@@ -729,9 +726,6 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
                                               tsk,
                                               bp->attr.disabled);
        }
-
-       if (!bp)
-               return -EIO;
        /*
         * CHECKME: the previous code returned -EIO if the addr wasn't a
         * valid task virtual addr. The new one will return -EINVAL in this

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 06d372f..dd3fb4a 100644 (file)
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -442,7 +442,7 @@ register_wide_hw_breakpoint(unsigned long addr,
 
                *pevent = bp;
 
-               if (IS_ERR(bp) || !bp) {
+               if (IS_ERR(bp)) {
                        err = PTR_ERR(bp);
                        goto fail;
                }
@@ -453,7 +453,7 @@ register_wide_hw_breakpoint(unsigned long addr,
 fail:
        for_each_possible_cpu(cpu) {
                pevent = per_cpu_ptr(cpu_events, cpu);
-               if (IS_ERR(*pevent) || !*pevent)
+               if (IS_ERR(*pevent))
                        break;
                unregister_hw_breakpoint(*pevent);
        }

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 9f040e4..c538b15 100644 (file)
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -200,12 +200,9 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
        entry->ksym_hbp = register_wide_hw_breakpoint(entry->ksym_addr,
                                        entry->len, entry->type,
                                        ksym_hbp_handler, true);
+
        if (IS_ERR(entry->ksym_hbp)) {
-               entry->ksym_hbp = NULL;
                ret = PTR_ERR(entry->ksym_hbp);
-       }
-
-       if (!entry->ksym_hbp) {
                printk(KERN_INFO "ksym_tracer request failed. Try again"
                                        " later!!\n");
                goto err;
@@ -332,21 +329,16 @@ static ssize_t ksym_trace_filter_write(struct file *file,
        if (changed) {
                unregister_wide_hw_breakpoint(entry->ksym_hbp);
                entry->type = op;
+               ret = 0;
                if (op > 0) {
                        entry->ksym_hbp =
                                register_wide_hw_breakpoint(entry->ksym_addr,
                                        entry->len, entry->type,
                                        ksym_hbp_handler, true);
                        if (IS_ERR(entry->ksym_hbp))
-                               entry->ksym_hbp = NULL;
-
-                       /* modified without problem */
-                       if (entry->ksym_hbp) {
-                               ret = 0;
+                               ret = PTR_ERR(entry->ksym_hbp);
+                       else
                                goto out;
-                       }
-               } else {
-                       ret = 0;
                }
                /* Error or "symbol:---" case: drop it */
                ksym_filter_entry_count--;

diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index 9506381..ee7f9fb 100644 (file)
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -61,9 +61,6 @@ static int __init hw_break_module_init(void)
        if (IS_ERR(sample_hbp)) {
                ret = PTR_ERR(sample_hbp);
                goto fail;
-       } else if (!sample_hbp) {
-               ret = -EINVAL;
-               goto fail;
        }
 
        printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);