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| author | Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | 2006-04-10 22:53:37 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-04-11 06:18:36 -0700 |
| commit | b1c332c9e813cbee6ca77c3a66ee4d312eb96770 (patch) | |
| tree | 8ce0329e77d6c293b0c15ef1d163a81cb1e1a950 | |
| parent | e6fb54abb8a36703f54b7e27a756a3df6667c37b (diff) | |
| download | blackbird-op-linux-b1c332c9e813cbee6ca77c3a66ee4d312eb96770.tar.gz blackbird-op-linux-b1c332c9e813cbee6ca77c3a66ee4d312eb96770.zip | |
[PATCH] uml: fix hang on run_helper() failure on uml_net
Fix an hang on a pipe when run_helper() fails when called by change_tramp()
(i.e. when calling uml_net) - reproduced the bug and verified this fixes it.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | arch/um/drivers/net_user.c | 4 | ||||
| -rw-r--r-- | arch/um/os-Linux/helper.c | 10 |
2 files changed, 8 insertions, 6 deletions
diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c index 0e2f06187ea7..0a7786e00cfb 100644 --- a/arch/um/drivers/net_user.c +++ b/arch/um/drivers/net_user.c @@ -182,7 +182,9 @@ static int change_tramp(char **argv, char *output, int output_len) pe_data.stdout = fds[1]; pid = run_helper(change_pre_exec, &pe_data, argv, NULL); - read_output(fds[0], output, output_len); + if (pid > 0) /* Avoid hang as we won't get data in failure case. */ + read_output(fds[0], output, output_len); + os_close_file(fds[0]); os_close_file(fds[1]); diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c index 6490a4ff40ac..6987d1d247a2 100644 --- a/arch/um/os-Linux/helper.c +++ b/arch/um/os-Linux/helper.c @@ -43,7 +43,7 @@ static int helper_child(void *arg) (*data->pre_exec)(data->pre_data); execvp(argv[0], argv); errval = errno; - printk("execvp of '%s' failed - errno = %d\n", argv[0], errno); + printk("helper_child - execve of '%s' failed - errno = %d\n", argv[0], errno); os_write_file(data->fd, &errval, sizeof(errval)); kill(os_getpid(), SIGKILL); return(0); @@ -92,15 +92,15 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv, close(fds[1]); fds[1] = -1; - /*Read the errno value from the child.*/ + /* Read the errno value from the child, if the exec failed, or get 0 if + * the exec succeeded because the pipe fd was set as close-on-exec. */ n = os_read_file(fds[0], &ret, sizeof(ret)); - if(n < 0){ + if (n < 0) { printk("run_helper : read on pipe failed, ret = %d\n", -n); ret = n; kill(pid, SIGKILL); CATCH_EINTR(waitpid(pid, NULL, 0)); - } - else if(n != 0){ + } else if(n != 0){ CATCH_EINTR(n = waitpid(pid, NULL, 0)); ret = -errno; } else { |
