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Thu, 24 Apr 2025 05:06:28 -0700 (PDT) Received: from [127.0.1.1] ([2a01:cb1d:dc:7e00:6266:7750:57ce:7cb4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a06d4c108esm1881793f8f.40.2025.04.24.05.06.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Apr 2025 05:06:27 -0700 (PDT) From: Bartosz Golaszewski Date: Thu, 24 Apr 2025 14:06:16 +0200 Subject: [PATCH libgpiod 1/2] core: keep memory usage of struct line_config in check Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250424-line_config_mem_use-v1-1-fa0abdcf0cdf@linaro.org> References: <20250424-line_config_mem_use-v1-0-fa0abdcf0cdf@linaro.org> In-Reply-To: <20250424-line_config_mem_use-v1-0-fa0abdcf0cdf@linaro.org> To: Kent Gibson , Linus Walleij Cc: linux-gpio@vger.kernel.org, Bartosz Golaszewski X-Mailer: b4 0.14.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=2383; i=bartosz.golaszewski@linaro.org; h=from:subject:message-id; bh=OpiXCiS8GEaSSqvMr+cMwA6cA9s2uZH8AiFO6/NdaCA=; b=owEBbQKS/ZANAwAKARGnLqAUcddyAcsmYgBoCilCk2YJ2IxON8nBtlOaLTzvyKjQQ4CN/MHk/ Or/xEJvcNyJAjMEAAEKAB0WIQQWnetsC8PEYBPSx58Rpy6gFHHXcgUCaAopQgAKCRARpy6gFHHX cu0aD/oCVdq+nnfqm/V5K8/TK89LAEmIyTmZho+7XJ+izrnN3CNRDjTmglT2ufJTfrLPDQXV1l1 9LpSN/wJ0/SZxlcDOOxcMzFG08HYlbBw/UxZOpMgR9GkN8HfWrhG8od9Mi62tAOFLLiSdhri10k QUoEuXxgwmAOsHWjAea9UE9QtgbcUSMFqHyPUpKzN58FzoefgUvrt+gBBgSMJrFzMg/WaNymNV3 zEMIsCdL2gUjaD7eeU7gV0vb2QVqrz/ns9Ha8VQROI3RWYfR3ggB2ktZ46Dtk9ZEHKtU7JAcdbe wBkCE9DPiQ1GLbcpBZMKe93lB29NOQiL06eccBYe8zrn8XONPz51HvrsC47CPRGaiAjieYCCcVD tOnMvQUIX/kAprUkdHhylJr9NQZ2JMtgPlvU9dS5OzVFJKG9rNBuTxvxBsJNIG+rrTiicZoF3M9 O/Y1zfSiTyOUrB0o8AboKyST+dtDSSEuHqw3+PH8Oxn8tyebsqXkStBT2oPhx0n0smLxoqK56ma OQAQj0Y1iqnh2QwAt32H+PeXnbBl/onAizj9AQ/Tdm5L6jfswXBG23399U4IuXrqxUTAHa70oSO IwCJjgyuOvYZWwcFbrBVrOUz74rO9Mzj3lJFlp9kMdzByBg15n/HnysIVUBcnLs1v1t26oA8K4g qpLjTUmBIHE1LfA== X-Developer-Key: i=bartosz.golaszewski@linaro.org; a=openpgp; fpr=169DEB6C0BC3C46013D2C79F11A72EA01471D772 From: Bartosz Golaszewski We keep a single instance of a struct gpiod_line_settings object shared by all offsets using it. Everytime gpiod_line_config_add_line_settings() is called, we append it to the per-line-config linked list and reference it from every per-offset structure. However we don't keep track of the offsets referencing a settings object and don't remove it when there are no more offsets associated with it - we only do it when the user frees or resets the line-config object. Extend the settings_node structure: make it a doubly-linked list - allowing to easily remove individual nodes - and add a reference count. Keep track of how many offsets reference a line-settings object and when that reference count drops to 0, remove it. Fixes: b7ba732e6a93 ("treewide: libgpiod v2 implementation") Closes: https://github.com/brgl/libgpiod/issues/130 Signed-off-by: Bartosz Golaszewski --- lib/line-config.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/lib/line-config.c b/lib/line-config.c index 9302c1b..24357f3 100644 --- a/lib/line-config.c +++ b/lib/line-config.c @@ -13,8 +13,10 @@ #define LINES_MAX (GPIO_V2_LINES_MAX) struct settings_node { + struct settings_node *prev; struct settings_node *next; struct gpiod_line_settings *settings; + unsigned int refcnt; }; struct per_line_config { @@ -93,7 +95,7 @@ GPIOD_API int gpiod_line_config_add_line_settings( size_t num_offsets, struct gpiod_line_settings *settings) { struct per_line_config *per_line; - struct settings_node *node; + struct settings_node *node, *old; size_t i; assert(config); @@ -121,14 +123,29 @@ GPIOD_API int gpiod_line_config_add_line_settings( return -1; } + node->refcnt = 0; node->next = config->sref_list; + if (config->sref_list) + config->sref_list->prev = node; + node->prev = NULL; config->sref_list = node; for (i = 0; i < num_offsets; i++) { per_line = find_config(config, offsets[i]); + node->refcnt++; per_line->offset = offsets[i]; + old = per_line->node; per_line->node = node; + + if (old && !(--old->refcnt)) { + if (old->prev) + old->prev->next = old->next; + if (old->next) + old->next->prev = old->prev; + free(old->settings); + free(old); + } } return 0;