block/curl: fix concurrent completion handling
curl_multi_check_completion would bail upon the first completed transfer even if more completion messages were available thus leaving some in flight IOs stuck. Rework a bit the loop to make the iterations clearer and drop the breaks. The original hang can be somewhat reproduced with the following command: $ qemu-img convert -p -m 16 -O qcow2 -c --image-opts \ 'file.driver=https,file.url=https://scaleway.testdebit.info/10G.iso,file.readahead=1M' \ /tmp/test.qcow2 Fixes: 1f2cead32443 ("curl: Ensure all informationals are checked for completion") Cc: qemu-stable@nongnu.org Signed-off-by: Antoine Damhet <adamhet@scaleway.com> Message-ID: <20260212162730.440855-2-adamhet@scaleway.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Antoine Damhet committed
Feb 12, 2026 at 17:27 UTC
6f7b0a23a6ea0cc72ad222ab37936248d99d4256
1 file changed
+2
-9
block/curl.c
+2
-9
@@ -324,17 +324,11 @@ curl_find_buf(BDRVCURLState *s, uint64_t start, uint64_t len, CURLAIOCB *acb)
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static void curl_multi_check_completion(BDRVCURLState *s)
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{
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int msgs_in_queue;
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+ CURLMsg *msg;
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/* Try to find done transfers, so we can free the easy
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* handle again. */
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- for (;;) {
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- CURLMsg *msg;
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- msg = curl_multi_info_read(s->multi, &msgs_in_queue);
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-
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- /* Quit when there are no more completions */
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- if (!msg)
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- break;
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-
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+ while ((msg = curl_multi_info_read(s->multi, &msgs_in_queue))) {
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if (msg->msg == CURLMSG_DONE) {
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int i;
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CURLState *state = NULL;
@@ -397,7 +391,6 @@ static void curl_multi_check_completion(BDRVCURLState *s)
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}
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curl_clean_state(state);
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- break;
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}
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}
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}