linux-kernel - [PATCH 0/3] tools/power turbostat: Fix segfault and restart loop issues

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Message-ID: <20251118155813.533424-1-darcari@redhat.com>
Date: Tue, 18 Nov 2025 10:58:10 -0500
From: David Arcari <darcari@...hat.com>
To: lenb@...nel.org
Cc: linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	David Arcari <darcari@...hat.com>
Subject: [PATCH 0/3] tools/power turbostat: Fix segfault and restart loop issues

This patch series addresses three stability issues found in turbostat,
primarily affecting virtualized environments where specific hardware
counters (like APERF) or MSR access may be restricted or inconsistent.

Patch 1 fixes a segmentation fault caused by referencing a NULL
fd_instr_count_percpu pointer. This occurs on systems where has_aperf
is 0 (preventing allocation), but has_aperf_access is 1 (allowing the
function call).

Patch 2 prevents an infinite loop when turbostat attempts to restart.
It ensures the restart limit is checked in all error paths and removes
logic that incorrectly reset the retry counter.

Patch 3 allows turbostat to proceed gracefully when APERF is unavailable.
Previously, the missing counter caused delta_thread() to error out,
triggering the restart mechanism.

David Arcari (3):
  tools/power turbostat: avoid segfault referencing
    fd_instr_count_percpu
  tools/power turbostat: avoid an infinite loop of restarts
  tools/power turbostat: allow turbostat to work when aperf is not
    available

 tools/power/x86/turbostat/turbostat.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

-- 
2.51.0