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[61.220.246.151]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8629b0cc638sm4434273b3a.57.2026.09.08.06.07.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Sep 2026 06:07:26 -0700 (PDT) From: Potin Lai Date: Tue, 08 Sep 2026 21:05:07 +0800 Subject: [libgpiod v1.6.5][PATCH] core: gracefully handle disappearing chips during iteration Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260908-gpiofind-error-enodev-v1-1-c7756aab9568@gmail.com> X-B4-Tracking: v=1; b=H4sIAAIIoGoC/yXMQQ6CMBBA0as0s3ZIIUrBqxAWtp3iGNOSqTYmh LtbdPkW/2+QSZgyXNUGQoUzp1jRnhS4+y0uhOyrodNdr0c94LJyChw9kkgSpJg8FTRktDsP1tA YoLarUODP7zvNf+e3fZB7HbPpyfb4eFXapm8uM+z7F2RfPIiKAAAA X-Change-ID: 20260908-gpiofind-error-enodev-7e70c48b7e9f To: linux-gpio@vger.kernel.org Cc: Cosmo Chou , Peter Yin , Potin Lai , Potin Lai X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1788872845; l=2232; i=potin.lai.pt@gmail.com; s=20260522; h=from:subject:message-id; bh=zUbYzyK4H/GKh+dAUruaqSkERYasj1NCBLqNSm11zjo=; b=zP5JUbQcbQBUCfUCl3d8/6i+w3w+HGNtiPaCHCKjGnZh5Zf9wFa/NAmph9p0ffREd2yY9YxSS hAO7BleQTFQBG2KtXJ6eurJ6X0mol+LIjuBPdjy2ZkHBR8e2/NQge8x X-Developer-Key: i=potin.lai.pt@gmail.com; a=ed25519; pk=j3/nMxzz1ZPpp1revghyZ8IqOnwi6RWfuxXN2XrNMRE= When hotpluggable GPIO controllers (like USB devices) are dynamically added or removed, a race condition can occur. A chip's device node might be present when iterating through /dev, but the chip could disappear by the time we try to open it or query its lines. Previously, this caused tools like 'gpiofind' to incorrectly abort with a 'No such device' (ENODEV) error if any chip on the system vanished during the search. Fix this by ignoring ENODEV errors when searching for a line (in gpiod_line_find()) and by silently skipping chips that fail to open during iteration (in gpiod_chip_iter_new()). Signed-off-by: Potin Lai --- lib/helpers.c | 2 +- lib/iter.c | 16 ++++------------ 2 files changed, 5 insertions(+), 13 deletions(-) diff --git a/lib/helpers.c b/lib/helpers.c index 479f370..6d1836a 100644 --- a/lib/helpers.c +++ b/lib/helpers.c @@ -423,7 +423,7 @@ struct gpiod_line *gpiod_line_find(const char *name) return line; } - if (errno != ENOENT) + if (errno != ENOENT && errno != ENODEV) goto out; } diff --git a/lib/iter.c b/lib/iter.c index bfd2852..7f5ad9a 100644 --- a/lib/iter.c +++ b/lib/iter.c @@ -51,7 +51,7 @@ struct gpiod_chip_iter *gpiod_chip_iter_new(void) if (!iter) goto err_free_dirs; - iter->num_chips = num_chips; + iter->num_chips = 0; iter->offset = 0; if (num_chips == 0) { @@ -64,23 +64,15 @@ struct gpiod_chip_iter *gpiod_chip_iter_new(void) goto err_free_iter; for (i = 0; i < num_chips; i++) { - iter->chips[i] = gpiod_chip_open_by_name(dirs[i]->d_name); - if (!iter->chips[i]) - goto err_close_chips; + iter->chips[iter->num_chips] = gpiod_chip_open_by_name(dirs[i]->d_name); + if (iter->chips[iter->num_chips]) + iter->num_chips++; } free_dirs(dirs, num_chips); return iter; -err_close_chips: - for (i = 0; i < num_chips; i++) { - if (iter->chips[i]) - gpiod_chip_close(iter->chips[i]); - } - - free(iter->chips); - err_free_iter: free(iter); --- base-commit: f1af4b189fb4074b08eecbc50cf33306299d6a51 change-id: 20260908-gpiofind-error-enodev-7e70c48b7e9f Best regards, -- Potin Lai