Hi,
Thanks for all your comments!
New version will be sent soon.
Regards,
Xiaoguang Wang
On 02/03/2015 05:57 PM, Cyril Hrubis wrote:
> Hi!
>> +/*
>> + * Copyright (c) 2015 Fujitsu Ltd.
>> + * Author: Xiaoguang Wang <wangxg.f...@cn.fujitsu.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
>> + * the GNU General Public License for more details.
>> + */
>> +
>> +/*
>> + * This is a regression test for commit:
>> + * http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/
>> + * commit/?id=90a8020
>> + * http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/
>> + * commit/?id=d6320cb
>> + */
>> +
>> +#define _GNU_SOURCE
>> +
>> +#include <stdio.h>
>> +#include <errno.h>
>> +#include <fcntl.h>
>> +#include <sys/types.h>
>> +#include <sys/wait.h>
>> +#include <unistd.h>
>> +#include <sys/mount.h>
>> +#include <sys/mman.h>
>> +
>> +#include "usctest.h"
>> +#include "test.h"
>> +#include "safe_macros.h"
>> +
>> +#define MNTPOINT "mntpoint"
>> +#define FS_BLOCKSIZE 1024
>> +
>> +static void setup(void);
>> +static void cleanup(void);
>> +static void do_child(void);
>> +static void do_test(void);
>> +
>> +static const char *device;
>> +static const char *fs_type = "ext4";
>> +static int mount_flag;
>> +
>> +static int page_size;
>> +static struct tst_checkpoint checkpoint1, checkpoint2;
>> +static int bug_reproduced;
>> +
>> +char *TCID = "mmap16";
>> +int TST_TOTAL = 1;
>> +
>> +int main(int ac, char **av)
>> +{
>> + int i;
>> + const char *msg;
>> +
>> + msg = parse_opts(ac, av, NULL, NULL);
>> + if (msg != NULL)
>> + tst_brkm(TBROK, NULL, "OPTION PARSING ERROR - %s", msg);
>> +
>> + setup();
>> +
>> + /*
>> + * If child process was killed by SIGBUS, indeed that can not guarantee
>> + * this bug must have been fixed, If luckily virtual memory subsystem
>> + * decides that it is time to write dirty pages, it will make maped
>> + * pages write-protect, so ->page_mkwrite() still will be called, child
>> + * process will be killed by SIGBUS, it's not fixed because of above
>> + * fixing patches. So here we run this test 10 times, if once, child
>> + * process exits normally, we can sure that this bug is not fixed.
>> + */
>> + for (i = 0; i < 10; i++)
>> + do_test();
>> +
>> + if (bug_reproduced)
>> + tst_resm(TFAIL, "Bug is reproduced!");
>> + else
>> + tst_resm(TPASS, "Bug is not reproduced!");
>> +
>> + cleanup();
>> + tst_exit();
>> +}
>> +
>> +static void do_test(void)
>> +{
>> + int fd, ret, status;
>> + pid_t child;
>> + char buf[FS_BLOCKSIZE];
>> +
>> + SAFE_TOUCH(cleanup, "testfilep", 0644, NULL);
>> + SAFE_TOUCH(cleanup, "testfilec", 0644, NULL);
>> +
>> + child = tst_fork();
>> + if (child < 0) {
>> + tst_brkm(TBROK | TERRNO, cleanup, "fork failed");
>> + } else if (child == 0) {
>> + do_child();
>> + } else {
>> + fd = SAFE_OPEN(cleanup, "testfilep", O_RDWR);
>> + memset(buf, 'a', FS_BLOCKSIZE);
>> +
>> + TST_CHECKPOINT_PARENT_WAIT(cleanup, &checkpoint1);
>> + while (1) {
>> + ret = write(fd, buf, FS_BLOCKSIZE);
>> + if (ret < 0) {
>> + if (errno == ENOSPC) {
>> + break;
>> + } else {
>> + tst_brkm(TBROK | TERRNO, cleanup,
>> + "write failed unexpectedly");
>> + }
>> + }
>> + }
>> + SAFE_CLOSE(cleanup, fd);
>> + TST_CHECKPOINT_SIGNAL_CHILD(cleanup, &checkpoint2);
>> + }
>
> I tend to write this code as
>
> switch (child) {
> case -1:
> tst_brkm(...);
> case 0:
> do_child();
> break;
> default:
> ...
> break;
> }
>
>> + wait(&status);
>> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGBUS) {
>> + ;
>
> This empty body if looks strange.
>
> Can't we just write this code as:
>
> if (WIFEXITED(status) && WEXITSTATUS(status) == 1) {
> bug_reproduced = 1;
> } else {
> if (!WIFSIGNALED(status) || WTERMSIG(status) != SIGBUS)) {
> tst_brkm(TBROK | TERRNO, cleanup,
> "child process terminate unexpectedly");
> }
> }
>
> Or add a TINFO message that the child has been killed with SIGBUS, so
> that the body is not empty at least?
>
>> + } else if (WIFEXITED(status) && WEXITSTATUS(status) == 1) {
>> + bug_reproduced = 1;
>> + } else {
>> + tst_brkm(TBROK | TERRNO, cleanup,
>> + "child process terminate unexpectedly");
>> + }
>> +
>> + SAFE_UNLINK(cleanup, "testfilep");
>> + SAFE_UNLINK(cleanup, "testfilec");
>> +}
>> +
>> +static void setup(void)
>> +{
>> + const char *fs_opts[3] = {"-b", "1024", NULL};
>> +
>> + tst_sig(FORK, DEF_HANDLER, NULL);
>> +
>> + TEST_PAUSE;
>> + tst_tmpdir();
>> +
>> + page_size = getpagesize();
>> + if (page_size == -1)
>> + tst_brkm(TBROK | TERRNO, cleanup, "Unable to get page size");
>> +
>> + device = tst_acquire_device(cleanup);
>> + if (!device)
>> + tst_brkm(TCONF, cleanup, "Failed to obtain block device");
>> + tst_mkfs(cleanup, device, fs_type, fs_opts);
>> +
>> + SAFE_MKDIR(cleanup, MNTPOINT, 0755);
>> + /*
>> + * Disable ext4 delalloc feature, so block will be allocated
>> + * as soon as possible
>> + */
>> + if (mount(device, MNTPOINT, fs_type, 0, "nodelalloc") < 0) {
>> + tst_brkm(TBROK | TERRNO, cleanup,
>> + "mount device:%s failed", device);
>> + }
>
> We do have SAFE_MOUNT() as well.
>
>> + mount_flag = 1;
>> +
>> + SAFE_CHDIR(cleanup, MNTPOINT);
>> + TST_CHECKPOINT_CREATE(&checkpoint1);
>> + TST_CHECKPOINT_CREATE(&checkpoint2);
>> +}
>> +
>> +static void do_child(void)
>> +{
>> + int fd, offset;
>> + char buf[FS_BLOCKSIZE];
>> + char *addr = NULL;
>> +
>> + /*
>> + * We have changed SIGBUS' handler in parent process,
>> + * so here just restore it
>> + */
>> + if (signal(SIGBUS, SIG_DFL) == SIG_ERR)
>> + tst_brkm(TBROK | TERRNO, NULL, "signal(SIGBUS) failed");
>> +
>> + memset(buf, 'a', FS_BLOCKSIZE);
>> + fd = SAFE_OPEN(NULL, "testfilec", O_RDWR);
>> + SAFE_PWRITE(NULL, 1, fd, buf, FS_BLOCKSIZE, 0);
>> +
>> + /*
>> + * In case mremap() may fail because that memory area can not be
>> + * expanded at current virtual address(MREMAP_MAYMOVE is not set),
>> + * we first do a mmap(page_size * 2) operation to reserve some
>> + * free address space.
>> + */
>> + addr = (char *)SAFE_MMAP(NULL, NULL, page_size * 2, PROT_WRITE |
>> + PROT_READ, MAP_PRIVATE_EXCEPT_UCLINUX|
>> + MAP_ANONYMOUS, -1, 0);
>
> Casting void* pointers to anything else is meaningless, please don't do
> that.
>
>> + SAFE_MUNMAP(NULL, addr, page_size * 2);
>> +
>> + addr = (char *)SAFE_MMAP(NULL, addr, FS_BLOCKSIZE, PROT_WRITE |
>> + PROT_READ, MAP_SHARED, fd, 0);
>> +
>> + addr[0] = 'a';
>> +
>> + SAFE_FTRUNCATE(NULL, fd, page_size * 2);
>> + addr = mremap(addr, FS_BLOCKSIZE, 2 * page_size, 0);
>> + if (addr == MAP_FAILED)
>> + tst_brkm(TBROK | TERRNO, NULL, "mremap failed unexpectedly");
>> +
>> + /*
>> + * Let parent process consume FS free blocks as many as possible, then
>> + * there'll be no free blocks allocated for this new file mmaping for
>> + * offset starting at 1024, 2048, or 3072. If this above kernel bug
>> + * has been fixed, usually child process will killed by SIGBUS signal,
>> + * if not, the data 'A', 'B', 'C' will be silently discarded later when
>> + * kernel writepage is called, that means data corruption.
>> + */
>> + TST_CHECKPOINT_SIGNAL_PARENT(&checkpoint1);
>> + TST_CHECKPOINT_CHILD_WAIT(&checkpoint2);
>> +
>> + for (offset = FS_BLOCKSIZE; offset < page_size; offset += FS_BLOCKSIZE)
>> + addr[offset] = 'a';
>> + exit(TFAIL);
>> +}
>> +
>> +static void cleanup(void)
>> +{
>> + TEST_CLEANUP;
>> +
>> + SAFE_CHDIR(NULL, "..");
>
> It's better not to use SAFE_MACROS here, because we wan't to run the
> rest of the cleanup even if this step fails. So what we should do here
> is just:
>
> if (chdir(".."))
> tst_resm(TWARN | TERRNO, "chdir('..') failed");
>
>> + if (mount_flag && tst_umount(MNTPOINT) < 0)
>> + tst_resm(TWARN | TERRNO, "umount device:%s failed", device);
>> +
>> + if (device)
>> + tst_release_device(NULL, device);
>> +
>> + tst_rmdir();
>> +}
>> --
>> 1.8.3.1
>>
>
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