From: Frank Ch. Eigler Date: Mon, 15 Aug 2022 10:20:10 +0000 (-0400) Subject: PR29474: debuginfod X-Git-Tag: elfutils-0.188~40 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=31d6b1fe74ab89138b4d256742997b730dc5cba8;p=thirdparty%2Felfutils.git PR29474: debuginfod Previous code sometimes confused debuginfod with concurrent queries targeting the same RPM. One thread fetching & prefetching, the other thread misinterpreted the sudden presence of its target file in the fdcache as a mere unnecessary prefetch duplicate. But if it was the other thread's target file, previous code would -skip- it completely, resulting in a 404 error. New code allows the other thread to also decompress the target file and return it, and still continue to its own prefetching process for other files. There's a performance trade-off here. Another option would be for the other thread to check the fdcache regularly and abort its own prefetch/fetch/prefetch loop early in case of a sudden target file hit. That'd save CPU probably but it'd stop prefetching of later segments of the input archive, which could save future time. Automated testing is too time/load sensitive to attempt. Confirmed working with Martin's stress tester. Reported-By: Martin Liška Signed-Off-By: Frank Ch. Eigler --- diff --git a/debuginfod/ChangeLog b/debuginfod/ChangeLog index a8b5d7f43..7cc9bcaf2 100644 --- a/debuginfod/ChangeLog +++ b/debuginfod/ChangeLog @@ -1,3 +1,9 @@ +2022-08-15 Frank Ch. Eigler + + PR29474 + * debuginfod.cxx (handle_buildid_r_match): Don't trigger false-404's + for concurrently prefetched target files. + 2022-08-02 Josef Cejka * debuginfod.cxx (groom): Don't evaluate regex unless needed. diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx index a089d0bd4..9245be53c 100644 --- a/debuginfod/debuginfod.cxx +++ b/debuginfod/debuginfod.cxx @@ -1742,7 +1742,8 @@ handle_buildid_r_match (bool internal_req_p, if ((r == 0) && (fn != b_source1)) // stage 1 continue; - if (fdcache.probe (b_source0, fn)) // skip if already interned + if (fdcache.probe (b_source0, fn) && // skip if already interned + fn != b_source1) // but only if we'd just be prefetching, PR29474 continue; // extract this file to a temporary file