linux-kernel - [tip:perf/core] hw_breakpoints: Release the bp slot if arch_validate_hwbkpt

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Date:	Fri, 29 Jan 2010 09:24:38 GMT
From:	tip-bot for Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, maneesh@...ibm.com, hpa@...or.com,
	mingo@...hat.com, mahesh@...ux.vnet.ibm.com, ananth@...ibm.com,
	fweisbec@...il.com, tglx@...utronix.de, prasad@...ux.vnet.ibm.com
Subject: [tip:perf/core] hw_breakpoints: Release the bp slot if arch_validate_hwbkpt_settings() fails.

Commit-ID:  b23ff0e9330e4b11e18af984d50573598e10e7f9
Gitweb:     http://git.kernel.org/tip/b23ff0e9330e4b11e18af984d50573598e10e7f9
Author:     Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>
AuthorDate: Thu, 21 Jan 2010 18:25:16 +0530
Committer:  Frederic Weisbecker <fweisbec@...il.com>
CommitDate: Thu, 28 Jan 2010 14:15:51 +0100

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@...ux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: K. Prasad <prasad@...ux.vnet.ibm.com>
Cc: Maneesh Soni <maneesh@...ibm.com>
LKML-Reference: <20100121125516.GA32521@...ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/hw_breakpoint.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 50dbd59..c030ae6 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;
 }
 
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