7:31 a.m.
Noticed this while helping to debug a CGroupV2 problem.
Michal Prívozník (2):
virCgroupV2DevicesAvailable: Print stringified errno in the debug log
virbpf: Set errno instead of reporting errors
po/POTFILES.in | 1 -
src/util/virbpf.c | 39 ++++++++++++-----------------------
src/util/vircgroupv2devices.c | 2 +-
3 files changed, 14 insertions(+), 28 deletions(-)
--
2.24.1
7:31 a.m.
New subject: [PATCH 1/2] virCgroupV2DevicesAvailable: Print stringified errno in the debug log
In the virCgroupV2DevicesAvailable() function we try to determine
whether CGroups version 2 are available. We do this by opening
what we believe is the CGroup mount point and issuing a BPF call.
When the call fails, a debug message is printed. However, the BPF
call sets errno too. Include it in the debug message to help us
with debugging.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/util/vircgroupv2devices.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/util/vircgroupv2devices.c b/src/util/vircgroupv2devices.c
index 445f9c53fc..d62ee12a05 100644
--- a/src/util/vircgroupv2devices.c
+++ b/src/util/vircgroupv2devices.c
@@ -55,7 +55,7 @@ virCgroupV2DevicesAvailable(virCgroupPtr group)
}
if (virBPFQueryProg(cgroupfd, 0, BPF_CGROUP_DEVICE, &progCnt, NULL) < 0) {
- VIR_DEBUG("failed to query cgroup progs");
+ VIR_DEBUG("failed to query cgroup progs: %s", g_strerror(errno));
return false;
}
--
2.24.1
7:31 a.m.
New subject: [PATCH 2/2] virbpf: Set errno instead of reporting errors
The virbpf module wraps syscalls to BPF. However, if the kernel
headers used at the compile time don't have support for BPF the
module offers stubs which return a negative one to signal error
to the caller. But there is a slight discrepancy between real
functions and these stubs. While the former set errno and return
-1 the latter report an error (without setting the errno) and
return -1. This is not optimal because the caller might see stale
errno and overwrite the error message with a less accurate one.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
po/POTFILES.in | 1 -
src/util/virbpf.c | 39 +++++++++++++--------------------------
2 files changed, 13 insertions(+), 27 deletions(-)
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 982f2ebc36..8af457aa36 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -227,7 +227,6 @@
@SRCDIR(a)/src/util/virauth.c
@SRCDIR(a)/src/util/virauthconfig.c
@SRCDIR(a)/src/util/virbitmap.c
-@SRCDIR(a)/src/util/virbpf.c
@SRCDIR(a)/src/util/vircgroup.c
@SRCDIR(a)/src/util/vircgroupbackend.c
@SRCDIR(a)/src/util/vircgroupbackend.h
diff --git a/src/util/virbpf.c b/src/util/virbpf.c
index dec8d0133a..987fc34ef4 100644
--- a/src/util/virbpf.c
+++ b/src/util/virbpf.c
@@ -302,8 +302,7 @@ virBPFCreateMap(unsigned int mapType G_GNUC_UNUSED,
unsigned int valSize G_GNUC_UNUSED,
unsigned int maxEntries G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -313,8 +312,7 @@ virBPFLoadProg(struct bpf_insn *insns G_GNUC_UNUSED,
int progType G_GNUC_UNUSED,
unsigned int insnCnt G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -324,8 +322,7 @@ virBPFAttachProg(int progfd G_GNUC_UNUSED,
int targetfd G_GNUC_UNUSED,
int attachType G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -335,8 +332,7 @@ virBPFDetachProg(int progfd G_GNUC_UNUSED,
int targetfd G_GNUC_UNUSED,
int attachType G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -348,8 +344,7 @@ virBPFQueryProg(int targetfd G_GNUC_UNUSED,
unsigned int *progcnt G_GNUC_UNUSED,
void *progids G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -357,8 +352,7 @@ virBPFQueryProg(int targetfd G_GNUC_UNUSED,
int
virBPFGetProg(unsigned int id G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -368,8 +362,7 @@ virBPFGetProgInfo(int progfd G_GNUC_UNUSED,
struct bpf_prog_info *info G_GNUC_UNUSED,
unsigned int **mapIDs G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -377,8 +370,7 @@ virBPFGetProgInfo(int progfd G_GNUC_UNUSED,
int
virBPFGetMap(unsigned int id G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -387,8 +379,7 @@ int
virBPFGetMapInfo(int mapfd G_GNUC_UNUSED,
struct bpf_map_info *info G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -398,8 +389,7 @@ virBPFLookupElem(int mapfd G_GNUC_UNUSED,
void *key G_GNUC_UNUSED,
void *val G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -409,8 +399,7 @@ virBPFGetNextElem(int mapfd G_GNUC_UNUSED,
void *key G_GNUC_UNUSED,
void *nextKey G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -420,8 +409,7 @@ virBPFUpdateElem(int mapfd G_GNUC_UNUSED,
void *key G_GNUC_UNUSED,
void *val G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
@@ -430,8 +418,7 @@ int
virBPFDeleteElem(int mapfd G_GNUC_UNUSED,
void *key G_GNUC_UNUSED)
{
- virReportSystemError(ENOSYS, "%s",
- _("BPF not supported with this kernel"));
+ errno = ENOSYS;
return -1;
}
#endif /* !HAVE_SYS_SYSCALL_H || !HAVE_DECL_BPF_PROG_QUERY */
--
2.24.1
6:46 a.m.
On 3/9/20 9:31 AM, Michal Privoznik wrote:
Noticed this while helping to debug a CGroupV2 problem.
Michal Prívozník (2):
virCgroupV2DevicesAvailable: Print stringified errno in the debug log
virbpf: Set errno instead of reporting errors
po/POTFILES.in | 1 -
src/util/virbpf.c | 39 ++++++++++++-----------------------
src/util/vircgroupv2devices.c | 2 +-
3 files changed, 14 insertions(+), 28 deletions(-)
Reviewed-by: Daniel Henrique Barboza <danielhb413(a)gmail.com>
1748
days inactive
1749
days old
3 comments
2 participants
participants (2)
-
Daniel Henrique Barboza -
Michal Privoznik