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Add patch to fix build with rawhide glibc 2.33.9000

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See the patch for information on why examples/ucontext-cp.c does not
build with rawhide's glibc 2.33.9000. I sent this patch upstream to
liburing and notified glibc of a potential incompatible change.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2021-04-13 16:05:34 +01:00
parent 5dd54637a2
commit b24796c292
2 changed files with 83 additions and 0 deletions
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82
0003-examples-ucontext-cp.c-cope-with-variable-SIGSTKSZ.patch Normal file
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@ -0,0 +1,82 @@
From 595b858eb0576d70884337a61ace3d98a411b949 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Tue, 13 Apr 2021 15:45:52 +0100
Subject: [PATCH] examples/ucontext-cp.c: cope with variable SIGSTKSZ
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
The size of C arrays at file scope must be constant. The following
compiler error occurs with recent upstream glibc (2.33.9000):
CC ucontext-cp
ucontext-cp.c:31:23: error: variably modified ‘stack_buf’ at file scope
31 | unsigned char stack_buf[SIGSTKSZ];
| ^~~~~~~~~
make[1]: *** [Makefile:26: ucontext-cp] Error 1
The following glibc commit changed SIGSTKSZ from a constant value to a
variable:
commit 6c57d320484988e87e446e2e60ce42816bf51d53
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Mon Feb 1 11:00:38 2021 -0800
sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305]
...
+# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
Allocate the stack buffer explicitly to avoid declaring an array at file
scope.
Cc: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
Perhaps the glibc change needs to be revised before releasing glibc 2.34
since it might break applications. That's up to the glibc folks. It
doesn't hurt for liburing to take a safer approach that copes with the
SIGSTKSZ change in any case.
---
examples/ucontext-cp.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/examples/ucontext-cp.c b/examples/ucontext-cp.c
index 0b2a6b5..ea0c934 100644
--- a/examples/ucontext-cp.c
+++ b/examples/ucontext-cp.c
@@ -28,7 +28,7 @@
typedef struct {
struct io_uring *ring;
- unsigned char stack_buf[SIGSTKSZ];
+ unsigned char *stack_buf;
ucontext_t ctx_main, ctx_fnew;
} async_context;
@@ -115,8 +115,13 @@ static int setup_context(async_context *pctx, struct io_uring *ring)
perror("getcontext");
return -1;
}
- pctx->ctx_fnew.uc_stack.ss_sp = &pctx->stack_buf;
- pctx->ctx_fnew.uc_stack.ss_size = sizeof(pctx->stack_buf);
+ pctx->stack_buf = malloc(SIGSTKSZ);
+ if (!pctx->stack_buf) {
+ perror("malloc");
+ return -1;
+ }
+ pctx->ctx_fnew.uc_stack.ss_sp = pctx->stack_buf;
+ pctx->ctx_fnew.uc_stack.ss_size = SIGSTKSZ;
pctx->ctx_fnew.uc_link = &pctx->ctx_main;
return 0;
@@ -174,6 +179,7 @@ static void copy_file_wrapper(arguments_bundle *pbundle)
free(iov.iov_base);
close(pbundle->infd);
close(pbundle->outfd);
+ free(pbundle->pctx->stack_buf);
free(pbundle->pctx);
free(pbundle);
--
2.30.2

1
liburing.spec
View File

@ -10,6 +10,7 @@ BuildRequires: gcc
BuildRequires: make
Patch1: 0001-spec-bump-version-to-2.0.patch
Patch2: 0002-spec-add-explicit-build-dependency-on-make.patch
Patch3: 0003-examples-ucontext-cp.c-cope-with-variable-SIGSTKSZ.patch
%description
Provides native async IO for the Linux kernel, in a fast and efficient