From: Stephen Hemminger <stephen@networkplumber.org>
To: dev@dpdk.org
Cc: Stephen Hemminger <stephen@networkplumber.org>,
Tyler Retzlaff <roretzla@linux.microsoft.com>,
Chengwen Feng <fengchengwen@huawei.com>,
Anatoly Burakov <anatoly.burakov@intel.com>
Subject: [PATCH v4] doc/eal: add signal safety warning
Date: Mon, 11 Jul 2022 16:04:48 -0700 [thread overview]
Message-ID: <20220711230448.557715-1-stephen@networkplumber.org> (raw)
In-Reply-To: <20220705204401.158650-1-stephen@networkplumber.org>
The DPDK is not designed to be used from a signal handler.
Add a notice in the documentation describing this limitation,
similar to Linux signal-safety manual page.
Bugzilla ID: 1030
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
Acked-by: Chengwen Feng <fengchengwen@huawei.com>
---
v4 - add more functions and clarify
v3 - mistake (ignore it)
.../prog_guide/env_abstraction_layer.rst | 70 +++++++++++++++++++
1 file changed, 70 insertions(+)
diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst b/doc/guides/prog_guide/env_abstraction_layer.rst
index 67842ae27207..35fbebe1be04 100644
--- a/doc/guides/prog_guide/env_abstraction_layer.rst
+++ b/doc/guides/prog_guide/env_abstraction_layer.rst
@@ -818,6 +818,76 @@ Known Issues
The debug statistics of rte_ring, rte_mempool and rte_timer are not supported in an unregistered non-EAL pthread.
+Signal Safety
+~~~~~~~~~~~~~
+
+ The Posix API defines an async-signal-safe function as one that can be safely
+ called from with a signal handler. Many DPDK functions are non-reentrant and
+ therefore are unsafe to call from a signal handler.
+
+ The kinds of issues that make DPDK functions unsafe can be understood when
+ one considers that much of the code in DPDK uses locks and other shared
+ resources. For example, calling ``rte_mempool_lookup()`` from a signal
+ would deadlock if the signal happened during previous call ``rte_mempool``
+ routines.
+
+ Other functions are not signal safe because they use one or more
+ library routines that are not themselves signal safe.
+ For example, calling ``rte_panic()`` is not safe in a signal handler
+ because it uses ``rte_log()`` and ``rte_log()`` calls the
+ ``syslog()`` library function which is in the list of
+ signal safe functions in
+ `Signal-Safety manual page <https://man7.org/linux/man-pages/man7/signal-safety.7.html>`_.
+
+ The set of functions that are expected to be async-signal-safe in DPDK
+ is shown in the following table. The functions not otherwise noted
+ are not async-signal-safe.
+
+.. csv-table:: **Signal Safe Functions**
+ :header: "Function"
+ :widths: 32
+
+ rte_dump_stack
+ rte_eal_get_lcore_state
+ rte_eal_get_runtime_dir
+ rte_eal_has_hugepages
+ rte_eal_has_pci
+ rte_eal_lcore_role
+ rte_eal_process_type
+ rte_eal_using_phys_addrs
+ rte_get_hpet_cycles
+ rte_get_hpet_hz
+ rte_get_main_lcore
+ rte_get_next_lcore
+ rte_get_tsc_hz
+ rte_hypervisor_get
+ rte_hypervisor_get_name
+ rte_lcore_count
+ rte_lcore_cpuset
+ rte_lcore_has_role
+ rte_lcore_index
+ rte_lcore_is_enabled
+ rte_lcore_to_cpu_id
+ rte_lcore_to_socket_id
+ rte_log_get_global_level
+ rte_log_get_level
+ rte_memory_get_nchannel
+ rte_memory_get_nrank
+ rte_reciprocal_value
+ rte_reciprocal_value_u64
+ rte_socket_count
+ rte_socket_id
+ rte_socket_id_by_idx
+ rte_strerror
+ rte_strscpy
+ rte_strsplit
+ rte_sys_gettid
+ rte_uuid_compare
+ rte_uuid_is_null
+ rte_uuid_parse
+ rte_uuid_unparse
+
+
cgroup control
~~~~~~~~~~~~~~
--
2.35.1
next prev parent reply other threads:[~2022-07-11 23:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-10 15:23 [PATCH] " Stephen Hemminger
2022-06-10 22:53 ` Tyler Retzlaff
2022-06-10 23:38 ` Stephen Hemminger
2022-06-10 23:42 ` Tyler Retzlaff
2022-06-11 1:37 ` fengchengwen
2022-06-11 16:50 ` Mattias Rönnblom
2022-07-05 20:44 ` [PATCH v2] " Stephen Hemminger
2022-07-11 21:15 ` Thomas Monjalon
2022-07-11 21:31 ` Stephen Hemminger
2022-10-21 19:58 ` Stephen Hemminger
2022-07-11 23:02 ` [PATCH v3] " Stephen Hemminger
2022-07-11 23:04 ` Stephen Hemminger [this message]
2022-11-09 23:17 ` [PATCH v4] " Stephen Hemminger
2022-11-15 16:21 ` David Marchand
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