Hi Jan,
On 3/7/2024 7:04 PM, Jan Beulich wrote:
On 07.03.2024 11:38, Henry Wang wrote:
Below error can be seen when doing Yocto build of the toolstack:
| io.c: In function 'p9_error':
| io.c:684:5: error: ignoring return value of 'strerror_r' declared
with attribute 'warn_unused_result' [-Werror=unused-result]
| 684 | strerror_r(err, ring->buffer, ring->ring_size);
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| cc1: all warnings being treated as errors
Fix the build by using strerror() to replace strerror_r(). Since
strerror() is thread-unsafe, use a separate local mutex to protect
the action. The steps would then become: Acquire the mutex first,
invoke strerror(), copy the string from strerror() to the designated
buffer and then drop the mutex.
Fixes: f4900d6d69b5 ("9pfsd: allow building with old glibc")
I will add this tag in v3.
Signed-off-by: Henry Wang <xin.wa...@amd.com>
Reviewed-by: Jan Beulich <jbeul...@suse.com>
Thanks!
albeit there are a number of cosmetic aspects I'd have done differently
(see bottom of mail). The one thing I'd really like to ask for it a
comment ...
--- a/tools/9pfsd/io.c
+++ b/tools/9pfsd/io.c
@@ -680,8 +680,18 @@ static bool name_ok(const char *str)
static void p9_error(struct ring *ring, uint16_t tag, uint32_t err)
{
unsigned int erroff;
+ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+ char *strerror_str;
+ RING_IDX strerror_len = 0, copy_len = 0;
+
... here explaining why strerror_r() isn't used. Unless other comments
arise and a v3 would be needed, I'd add
/*
* While strerror_r() exists, it comes in a POSIX and a GNU flavor.
* Let's try to avoid trying to be clever with determining which
* one it is that the underlying C library offers, when really we
* don't expect this function to be called very often.
*/
while committing.
Since I am working on a V3 which will be sent out soon, please don't
bother :) I will
handle it from my side.
Anyway it'll need a maintainer ack first.
+ pthread_mutex_lock(&mutex);
+ strerror_str = strerror(err);
+ strerror_len = strlen(strerror_str) + 1;
+ copy_len = min(strerror_len, ring->ring_size);
+ memcpy(ring->buffer, strerror_str, copy_len);
+ ((char *)(ring->buffer))[copy_len - 1] = '\0';
+ pthread_mutex_unlock(&mutex);
- strerror_r(err, ring->buffer, ring->ring_size);
erroff = add_string(ring, ring->buffer, strlen(ring->buffer));
fill_buffer(ring, P9_CMD_ERROR, tag, "SU",
erroff != ~0 ? ring->str + erroff : "cannot allocate memory",
pthread_mutex_lock(&mutex);
str = strerror(err);
len = min(strlen(str), ring->ring_size - 1);
This actually will fire below errors on my build env, hence I separated
them with a different variable.
tools/include/xen-tools/common-macros.h:38:21: error: comparison of
distinct pointer types lacks a cast [-Werror]
| 38 | (void) (&_x == &_y); \
| | ^~
| io.c:695:11: note: in expansion of macro 'min'
| 695 | len = min(strlen(str), MAX_ERRSTR_LEN - 1);;
| | ^~~
| cc1: all warnings being treated as errors
memcpy(ring->buffer, str, len);
((char *)ring->buffer)[len] = '\0';
pthread_mutex_unlock(&mutex);
I will follow your style in V3 if you don't have any specific comment on
the error that I posted above (plus also not strongly disagree with my
approach in v2).
Kind regards,
Henry
Jan
