Messages in this thread Patch in this message | | | Subject | Re: [PATCH 2/2] auth_gss: unregister gss_domain when unloading module | From | Trond Myklebust <> | Date | Sun, 29 Oct 2006 15:15:59 -0500 |
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On Sun, 2006-10-29 at 22:38 +0900, Akinobu Mita wrote: > Reloading rpcsec_gss_krb5 or rpcsec_gss_spkm3 hit duplicate > registration in svcauth_gss_register_pseudoflavor(). > (If DEBUG_PAGEALLOC is enabled, oops will happen at > auth_domain_put() --> hlist_del() with uninitialized hlist_node) > > svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name) > { > ... > > test = auth_domain_lookup(name, &new->h); > if (test != &new->h) { /* XXX Duplicate registration? */ > auth_domain_put(&new->h); > /* dangling ref-count... */ > ... > } > > This patch unregisters gss_domain and free it when unloading > modules. > > - Define svcauth_gss_unregister_pseudoflavor() > (doing the opposite of svcauth_gss_register_pseudoflavor()) > > - Call svcauth_gss_unregister_pseudoflavor() in gss_mech_free() > > Cc: Andy Adamson <andros@citi.umich.edu> > Cc: J. Bruce Fields <bfields@citi.umich.edu> > Cc: Trond Myklebust <Trond.Myklebust@netapp.com> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> > > net/sunrpc/auth_gss/gss_mech_switch.c | 4 ++++ > net/sunrpc/auth_gss/svcauth_gss.c | 6 +++--- > 2 files changed, 7 insertions(+), 3 deletions(-) > > Index: work-fault-inject/net/sunrpc/auth_gss/gss_mech_switch.c > =================================================================== > --- work-fault-inject.orig/net/sunrpc/auth_gss/gss_mech_switch.c > +++ work-fault-inject/net/sunrpc/auth_gss/gss_mech_switch.c > @@ -60,6 +60,9 @@ gss_mech_free(struct gss_api_mech *gm) > > for (i = 0; i < gm->gm_pf_num; i++) { > pf = &gm->gm_pfs[i]; > + if (!pf->auth_domain_name) > + continue; > + svcauth_gss_unregister_pseudoflavor(pf->auth_domain_name); > kfree(pf->auth_domain_name); > pf->auth_domain_name = NULL; > } > @@ -93,8 +96,11 @@ gss_mech_svc_setup(struct gss_api_mech * > goto out; > status = svcauth_gss_register_pseudoflavor(pf->pseudoflavor, > pf->auth_domain_name); > - if (status) > + if (status) { > + kfree(pf->auth_domain_name); > + pf->auth_domain_name = NULL; > goto out; > + } > } > return 0; > out: > Index: work-fault-inject/net/sunrpc/auth_gss/svcauth_gss.c > =================================================================== > --- work-fault-inject.orig/net/sunrpc/auth_gss/svcauth_gss.c > +++ work-fault-inject/net/sunrpc/auth_gss/svcauth_gss.c > @@ -765,10 +765,12 @@ svcauth_gss_register_pseudoflavor(u32 ps > > test = auth_domain_lookup(name, &new->h); > if (test != &new->h) { /* XXX Duplicate registration? */ > - auth_domain_put(&new->h); > - /* dangling ref-count... */ > - goto out; > + WARN_ON(1); > + stat = -EBUSY; > + kfree(new->h.name); > + goto out_free_dom; > } > + auth_domain_put(&new->h); > return 0; > > out_free_dom: > @@ -779,6 +781,19 @@ out: > > EXPORT_SYMBOL(svcauth_gss_register_pseudoflavor); > > +void svcauth_gss_unregister_pseudoflavor(char *name) > +{ > + struct auth_domain *dom; > + > + dom = auth_domain_find(name); > + if (dom) { > + auth_domain_put(dom); > + auth_domain_put(dom); > + } > +}
Strictly speaking, if you want to be smp-safe, you probably need something like the following:
dom = auth_domain_find(name); if (dom) { spin_lock(&auth_domain_lock); if (!hlist_unhashed(dom->hash)) { hlist_del_init(dom->hash); spin_unlock(&auth_domain_lock); auth_domain_put(dom); } else spin_unlock(&auth_domain_lock); auth_domain_put(dom); }
and then add a test for hlist_unhashed into auth_domain_put(). If not, some other processor could race you inside svcauth_gss_unregister_pseudoflavor.
However since all this is being done under the BKL, then your alternative above might be sufficient. The only question then would be why we need auth_domain_lock?
> +EXPORT_SYMBOL(svcauth_gss_unregister_pseudoflavor); > + > static inline int > read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj) > { > Index: work-fault-inject/include/linux/sunrpc/svcauth_gss.h > =================================================================== > --- work-fault-inject.orig/include/linux/sunrpc/svcauth_gss.h > +++ work-fault-inject/include/linux/sunrpc/svcauth_gss.h > @@ -22,6 +22,7 @@ > int gss_svc_init(void); > void gss_svc_shutdown(void); > int svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name); > +void svcauth_gss_unregister_pseudoflavor(char *name); > > #endif /* __KERNEL__ */ > #endif /* _LINUX_SUNRPC_SVCAUTH_GSS_H */
Cheers, Trond - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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