From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Date: Thu, 21 Jan 2010 12:55:16 +0000 (+0530)
Subject: hw_breakpoints: Release the bp slot if arch_validate_hwbkpt_settings() fails.
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=b23ff0e9330e4b11e18af984d50573598e10e7f9;p=openwrt%2Fstaging%2Fblogic.git

hw_breakpoints: Release the bp slot if arch_validate_hwbkpt_settings() fails.

On a given architecture, when hardware breakpoint registration fails
due to un-supported access type (read/write/execute), we lose the bp
slot since register_perf_hw_breakpoint() does not release the bp slot
on failure.
Hence, any subsequent hardware breakpoint registration starts failing
with 'no space left on device' error.

This patch introduces error handling in register_perf_hw_breakpoint()
function and releases bp slot on error.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: K. Prasad <prasad@linux.vnet.ibm.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
LKML-Reference: <20100121125516.GA32521@in.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 50dbd5999588..c030ae657f20 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -296,6 +296,10 @@ int register_perf_hw_breakpoint(struct perf_event *bp)
 	if (!bp->attr.disabled || !bp->overflow_handler)
 		ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
 
+	/* if arch_validate_hwbkpt_settings() fails then release bp slot */
+	if (ret)
+		release_bp_slot(bp);
+
 	return ret;
 }