[tip:perf/core] hw_breakpoints: Release the bp slot if arch_validate_hwbkpt_settings() fails.

From: tip-bot for Mahesh Salgaonkar
Date: Fri Jan 29 2010 - 04:25:27 EST

Commit-ID: b23ff0e9330e4b11e18af984d50573598e10e7f9
Gitweb: http://git.kernel.org/tip/b23ff0e9330e4b11e18af984d50573598e10e7f9
Author: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 21 Jan 2010 18:25:16 +0530
Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: K. Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Maneesh Soni <maneesh@xxxxxxxxxx>
LKML-Reference: <20100121125516.GA32521@xxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
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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