uprobes: Change prepare_uretprobe() to use uprobe_warn()

Turn the last pr_warn() in uprobes.c into uprobe_warn().

While at it:

   - s/kzalloc/kmalloc, we initialize every member of 'ri'

   - remove the pointless comment above the obvious code

Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134010.GA4752@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index eabdc21..4c941fe 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1541,9 +1541,9 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
                return;
        }
 
-       ri = kzalloc(sizeof(struct return_instance), GFP_KERNEL);
+       ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
        if (!ri)
-               goto fail;
+               return;
 
        trampoline_vaddr = get_trampoline_vaddr();
        orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs);
@@ -1561,8 +1561,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
                         * This situation is not possible. Likely we have an
                         * attack from user-space.
                         */
-                       pr_warn("uprobe: unable to set uretprobe pid/tgid=%d/%d\n",
-                                               current->pid, current->tgid);
+                       uprobe_warn(current, "handle tail call");
                        goto fail;
                }
 
@@ -1576,13 +1575,10 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
        ri->chained = chained;
 
        utask->depth++;
-
-       /* add instance to the stack */
        ri->next = utask->return_instances;
        utask->return_instances = ri;
 
        return;
-
  fail:
        kfree(ri);
 }