76 lines
2.7 KiB
Diff
76 lines
2.7 KiB
Diff
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From 2c909bc3b8594943c4306ec78e8c13327ca16284 Mon Sep 17 00:00:00 2001
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From: "Richard W.M. Jones" <rjones@redhat.com>
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Date: Wed, 21 Jun 2023 22:41:43 +0100
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Subject: [PATCH] ocaml: Release runtime lock around call to nbd_close
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OCaml 5 is stricter than earlier versions about correct locking.
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We must release the OCaml runtime lock when calling nbd_close since it
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may do some long-running operations and we want to allow concurrent
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threads to run.
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However specifically if there are callbacks (eg. a debug callback)
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then we would end up trying to re-acquire the lock in the callback,
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resulting in a crash:
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(gdb) bt
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#0 __pthread_kill_implementation (threadid=<optimized out>,
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signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
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#1 0x00007f47ffc8f773 in __pthread_kill_internal (signo=6,
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threadid=<optimized out>) at pthread_kill.c:78
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#2 0x00007f47ffc3e71e in __GI_raise (sig=sig@entry=6)
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at ../sysdeps/posix/raise.c:26
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#3 0x00007f47ffc2687f in __GI_abort () at abort.c:79
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#4 0x0000560c9eb62779 in caml_fatal_error ()
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#5 0x0000560c9eb63238 in caml_plat_fatal_error ()
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#6 0x0000560c9eb4ea77 in caml_acquire_domain_lock ()
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#7 0x0000560c9eb65cdc in caml_leave_blocking_section ()
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#8 0x0000560c9eaf8a87 in debug_wrapper (user_data=0x560ca0af2670,
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context=0x7f47fff8ca60 "nbd_close", msg=0x560ca0af28b0 "closing handle")
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at ../nbd-c.c:187
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#9 0x00007f47fff7072f in nbd_internal_debug (h=h@entry=0x560ca0b57db0,
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context=0x7f47fff8ca60 "nbd_close", context@entry=0x0,
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fs=fs@entry=0x7f47fff8ca6a "closing handle")
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at /home/rjones/d/libnbd/lib/debug.c:90
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#10 0x00007f47fff73f23 in nbd_close (h=0x560ca0b57db0)
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at /home/rjones/d/libnbd/lib/handle.c:127
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#11 0x0000560c9eae8dbe in nbd_internal_ocaml_handle_finalize (
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hv=<optimized out>) at ../handle.c:39
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#12 nbd_internal_ocaml_nbd_close (hv=<optimized out>) at ../handle.c:62
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#13 <signal handler called>
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#14 0x0000560c9eae84dc in camlTest_140_explicit_close__entry () at NBD.ml:148
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#15 0x0000560c9eae5c5b in caml_program ()
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#16 <signal handler called>
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#17 0x0000560c9eb6cb77 in caml_startup_common ()
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#18 0x0000560c9eb6cbef in caml_main ()
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#19 0x0000560c9eae5910 in main ()
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---
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ocaml/handle.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/ocaml/handle.c b/ocaml/handle.c
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index fb45b30102..b3e5a0fc33 100644
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--- a/ocaml/handle.c
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+++ b/ocaml/handle.c
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@@ -26,6 +26,7 @@
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#include <caml/fail.h>
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#include <caml/memory.h>
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#include <caml/mlvalues.h>
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+#include <caml/threads.h>
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#include <libnbd.h>
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@@ -36,7 +37,9 @@ nbd_internal_ocaml_handle_finalize (value hv)
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{
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struct nbd_handle *h = NBD_val (hv);
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+ caml_enter_blocking_section ();
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nbd_close (h);
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+ caml_leave_blocking_section ();
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}
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value
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--
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2.41.0
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