When trying to print a specific class layout with recent pahole
versions, we get an error right after the expected class print:
$ ./build/pahole -C test_bin_struct_packed -F dwarf tests/bin/test_bin
struct test_bin_struct_packed {
char a; /* 0 1 */
short int b; /* 1 2 */
int c; /* 3 4 */
long long unsigned int d; /* 7 8 */
/* size: 15, cachelines: 1, members: 4 */
/* last cacheline: 15 bytes */
} __attribute__((__packed__));
pahole: /home/alexis/src/pahole/tests/bin/test_bin: Invalid argument
This error is due to pahole_stealer returning LSK__STOP_LOADING when
dealing with a single class and when it is done. This LSK__STOP_LOADING
is then propagated to dwarf_loader__worker_thread and interpreted as an
error (and turned into a DWARF_CB_ABORT). The main issue is that this
LSK__STOP_LOADING value is sometimes generated by actual issues during
pahole stealing, sometimes by "nominal" execution.
Add a new LSK__ABORT status to distinguish between those nominal and
faulty cases. Still let DWARF_CB_ABORT value propagate when the stealer
returns either LSK__ABORT or LSK__STOP_LOADING (so that any other
running worker is properly asked to stop, thanks to
cus_processsing_queue.abort), but also propagate the LSK status, and
return an error on DWARF_CB_ABORT only if the status is LSK__ABORT.
Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@xxxxxxxxxxx>
---
Changes in v3:
- renamed out_abort to out_early in dwarf_loader__worker_thread as well
- replaced goto dump_and_abort with early returns in pahole_stealer to
simplify the final return block
- collected Alan's R-b
- Link to v2: https://lore.kernel.org/r/20250730-lsk__abort-v2-1-fcec3172a878@xxxxxxxxxxx
Changes in v2:
- rename out_error to out_early in dwarf_loader__worker_thread
- Introduced lsk_status in struct_dwarf_cus, which hold a worker LSK
return status
- keep returning DWARF_CB_ABORT if worker returns LSK__STOP_LOADING
- in cus__load_module, do not return an error is lsk_status is different
from LSK__ABORT
- Link to v1: https://lore.kernel.org/r/20250716-lsk__abort-v1-1-586f31a9d97d@xxxxxxxxxxx
---
See [1] for original discussions about the issue
[1] https://lore.kernel.org/dwarves/DB5VWHU0N27I.3ETC4G47KB9Q@xxxxxxxxxxx/
---
dwarf_loader.c | 29 +++++++++++++++++++----------
dwarves.h | 1 +
pahole.c | 18 ++++++++----------
3 files changed, 28 insertions(+), 20 deletions(-)
diff --git a/dwarf_loader.c b/dwarf_loader.c
index ef00cdf308166732fc0938f2eecd56d314d3354f..ea692b295ab6340897ac16466fbe6776724c6186 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -3277,6 +3277,8 @@ static int cus__steal_now(struct cus *cus, struct cu *cu, struct conf_load *conf
break;
case LSK__KEEPIT:
break;
+ case LSK__ABORT:
+ break;
}
return lsk;
}
@@ -3439,6 +3441,7 @@ struct dwarf_cus {
const unsigned char *build_id;
int build_id_len;
int error;
+ int lsk_status;
struct dwarf_cu *type_dcu;
uint32_t nr_cus_created;
};
@@ -3657,11 +3660,12 @@ static void *dwarf_loader__worker_thread(void *arg)
struct dwarf_cus *dcus = arg;
bool stop = false;
struct cu *cu;
+ int ret;
while (!stop) {
job = cus_queue__enqdeq_job(job);
if (!job)
- goto out_abort;
+ goto out_early;
switch (job->type) {
@@ -3679,8 +3683,11 @@ static void *dwarf_loader__worker_thread(void *arg)
break;
case JOB_STEAL:
- if (cus__steal_now(dcus->cus, job->cu, dcus->conf) == LSK__STOP_LOADING)
- goto out_abort;
+ ret = cus__steal_now(dcus->cus, job->cu, dcus->conf);
+ if (ret == LSK__ABORT || ret == LSK__STOP_LOADING) {
+ dcus->lsk_status = ret;
+ goto out_early;
+ }
cus_queue__inc_next_cu_id();
/* re-enqueue JOB_DECODE so that next CU is decoded from DWARF */
job->type = JOB_DECODE;
@@ -3689,15 +3696,15 @@ static void *dwarf_loader__worker_thread(void *arg)
default:
fprintf(stderr, "Unknown dwarf_loader job type %d\n", job->type);
- goto out_abort;
+ goto out_early;
}
}
if (dcus->error)
- goto out_abort;
+ goto out_early;
return (void *)DWARF_CB_OK;
-out_abort:
+out_early:
__atomic_store_n(&cus_processing_queue.abort, true, __ATOMIC_SEQ_CST);
pthread_cond_signal(&cus_processing_queue.job_added);
return (void *)DWARF_CB_ABORT;
@@ -3750,7 +3757,7 @@ static int dwarf_cus__process_cus(struct dwarf_cus *dcus)
job = calloc(1, sizeof(*job));
if (!job) {
dcus->error = -ENOMEM;
- goto out_error;
+ goto out_early;
}
job->type = JOB_DECODE;
/* no need for locks, workers were not started yet */
@@ -3776,7 +3783,7 @@ out_join:
dcus->error = (long)res;
}
-out_error:
+out_early:
cus_queue__destroy();
return dcus->error;
@@ -3872,7 +3879,7 @@ static int cus__merge_and_process_cu(struct cus *cus, struct conf_load *conf,
goto out_abort;
cu__finalize(cu, cus, conf);
- if (cus__steal_now(cus, cu, conf) == LSK__STOP_LOADING)
+ if (cus__steal_now(cus, cu, conf) == LSK__ABORT)
goto out_abort;
return 0;
@@ -3897,6 +3904,7 @@ static int cus__load_module(struct cus *cus, struct conf_load *conf,
struct cu *type_cu;
struct dwarf_cu type_dcu;
int type_lsk = LSK__KEEPIT;
+ int lsk_worker_status = LSK__ABORT;
int res = __cus__load_debug_types(cus, conf, mod, dw, elf, filename, build_id, build_id_len, &type_cu, &type_dcu);
if (res != 0) {
@@ -3930,9 +3938,10 @@ static int cus__load_module(struct cus *cus, struct conf_load *conf,
.nr_cus_created = 0,
};
res = dwarf_cus__process_cus(&dcus);
+ lsk_worker_status = dcus.lsk_status;
}
- if (res)
+ if (res && lsk_worker_status == LSK__ABORT)
return res;
if (type_lsk == LSK__DELETE)
diff --git a/dwarves.h b/dwarves.h
index 883852f4b60a36d73bce4568cbacd8ef3cff97ea..5df1cdad9be36212bd6548e86180860daffa3f63 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -43,6 +43,7 @@ enum load_steal_kind {
LSK__KEEPIT,
LSK__DELETE,
LSK__STOP_LOADING,
+ LSK__ABORT,
};
/*
diff --git a/pahole.c b/pahole.c
index 333e71ab65924d2c64771be7d40f768f02e9a0f0..92b7c5d1da188a2e5fcf07df637bd6a3b92babb5 100644
--- a/pahole.c
+++ b/pahole.c
@@ -3165,13 +3165,13 @@ static enum load_steal_kind pahole_stealer__btf_encode(struct cu *cu, struct con
if (!btf_encoder) {
fprintf(stderr, "Error creating BTF encoder.\n");
- return LSK__STOP_LOADING;
+ return LSK__ABORT;
}
err = btf_encoder__encode_cu(btf_encoder, cu, conf_load);
if (err < 0) {
fprintf(stderr, "Error while encoding BTF.\n");
- return LSK__STOP_LOADING;
+ return LSK__ABORT;
}
return LSK__DELETE;
@@ -3230,7 +3230,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu, struct conf_load *conf
*
* FIXME: Disabled, should use Oracle's libctf
*/
- goto dump_and_stop;
+ return LSK__ABORT;
}
#endif
if (class_name == NULL) {
@@ -3281,7 +3281,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu, struct conf_load *conf
if (prototype->nr_args != 0 && !tag__is_struct(class)) {
fprintf(stderr, "pahole: attributes are only supported with 'class' and 'struct' types\n");
- goto dump_and_stop;
+ return LSK__ABORT;
}
struct type *type = tag__type(class);
@@ -3291,7 +3291,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu, struct conf_load *conf
if (type->sizeof_member == NULL) {
fprintf(stderr, "pahole: the sizeof member '%s' wasn't found in the '%s' type\n",
prototype->size, prototype->name);
- goto dump_and_stop;
+ return LSK__ABORT;
}
}
@@ -3300,7 +3300,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu, struct conf_load *conf
if (type->type_member == NULL) {
fprintf(stderr, "pahole: the type member '%s' wasn't found in the '%s' type\n",
prototype->type, prototype->name);
- goto dump_and_stop;
+ return LSK__ABORT;
}
}
@@ -3315,7 +3315,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu, struct conf_load *conf
if (type->filter == NULL) {
fprintf(stderr, "pahole: invalid filter '%s' for '%s'\n",
prototype->filter, prototype->name);
- goto dump_and_stop;
+ return LSK__ABORT;
}
}
@@ -3386,10 +3386,8 @@ static enum load_steal_kind pahole_stealer(struct cu *cu, struct conf_load *conf
/*
* If we found all the entries in --class_name, stop
*/
- if (list_empty(&class_names)) {
-dump_and_stop:
+ if (list_empty(&class_names))
ret = LSK__STOP_LOADING;
- }
dump_it:
if (first_obj_only)
ret = LSK__STOP_LOADING;
---
base-commit: 9845339bd09f9889dd741ed94f71eb92008dcdfc
change-id: 20250716-lsk__abort-2b517860af28
Best regards,
--
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
