| Message ID | cbb751a7fab10d228513bb163c85c83d025330c9.1722265284.git.matthew.barnes@cloud.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [XEN,v6] tools/lsevtchn: Use errno macro to handle hypercall error cases | expand |
On Mon, Jul 29, 2024 at 04:02:41PM +0100, Matthew Barnes wrote: > diff --git a/tools/xcutils/lsevtchn.c b/tools/xcutils/lsevtchn.c > index d1710613ddc5..29504c9d2077 100644 > --- a/tools/xcutils/lsevtchn.c > +++ b/tools/xcutils/lsevtchn.c > @@ -24,7 +25,28 @@ int main(int argc, char **argv) > status.port = port; > rc = xc_evtchn_status(xch, &status); > if ( rc < 0 ) > - break; > + { > + switch ( errno ) > + { > + case EACCES: /* Xen-owned evtchn */ > + continue; > + > + case EINVAL: /* Port enumeration has ended */ > + rc = 0; > + break; > + > + case ESRCH: > + perror("Domain ID does not correspond to valid domain"); I think this is going to print: "Domain ID does not correspond to valid domain: No such process" > + rc = ESRCH; So, `rc` is going to be the value returned by main(), that is the exit value of the program `lsevtchn`. Having different exit value might be useful sometime to distinguish between different errors but that would at least need to be written in some document. Can we just return "1" here on error? (I mean "rc = 1") > + break; > + > + default: > + perror(NULL); It would be slightly more useful to print which function fails, simply with: perror("xc_evtchn_status"); > + rc = errno; Same here, just "rc=1" should be good enough. Then if someone want to know why `lsevtchn` failed, they can read the error messages. At least, errno is likely to be between 0 and 255, but still, usually not very useful as an exit value for a program. > + break; > + } > + goto out; > + } > > if ( status.status == EVTCHNSTAT_closed ) > continue; > @@ -58,7 +80,8 @@ int main(int argc, char **argv) > printf("\n"); > } > > + out: > xc_interface_close(xch); > > - return 0; > + return rc; > } Thanks,
diff --git a/tools/xcutils/lsevtchn.c b/tools/xcutils/lsevtchn.c index d1710613ddc5..29504c9d2077 100644 --- a/tools/xcutils/lsevtchn.c +++ b/tools/xcutils/lsevtchn.c @@ -3,6 +3,7 @@ #include <stdint.h> #include <string.h> #include <stdio.h> +#include <errno.h> #include <xenctrl.h> @@ -24,7 +25,28 @@ int main(int argc, char **argv) status.port = port; rc = xc_evtchn_status(xch, &status); if ( rc < 0 ) - break; + { + switch ( errno ) + { + case EACCES: /* Xen-owned evtchn */ + continue; + + case EINVAL: /* Port enumeration has ended */ + rc = 0; + break; + + case ESRCH: + perror("Domain ID does not correspond to valid domain"); + rc = ESRCH; + break; + + default: + perror(NULL); + rc = errno; + break; + } + goto out; + } if ( status.status == EVTCHNSTAT_closed ) continue; @@ -58,7 +80,8 @@ int main(int argc, char **argv) printf("\n"); } + out: xc_interface_close(xch); - return 0; + return rc; }
Currently, lsevtchn aborts its event channel enumeration when it hits an event channel that is owned by Xen. lsevtchn does not distinguish between different hypercall errors, which results in lsevtchn missing potential relevant event channels with higher port numbers. Use the errno macro to distinguish between hypercall errors, and continue event channel enumeration if the hypercall error is not critical to enumeration. Signed-off-by: Matthew Barnes <matthew.barnes@cloud.com> --- Changes in v6: - Add blank space before label Changes in v5: - Code style changes to switch statement Changes in v4: - Catch non-critical errors and fail on everything else, instead of catching few known critical errors and ignoring everything else - Use 'perror' to describe miscellaneous critical errors - Return appropriate error code from lsevtchn tool - Tweak commit description --- tools/xcutils/lsevtchn.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-)