| Message ID | babc429d-6440-92aa-e1d0-eee2636a8d0f@users.sourceforge.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, May 20, 2017 at 04:32:17PM +0200, SF Markus Elfring wrote: > From: Markus Elfring <elfring@users.sourceforge.net> > Date: Sat, 20 May 2017 15:50:30 +0200 > > Omit seven extra messages for memory allocation failures in these functions. > > This issue was detected by using the Coccinelle software. > > Link: http://events.linuxfoundation.org/sites/events/files/slides/LCJ16-Refactor_Strings-WSang_0.pdf Please include an actual explanation for this change instead of linking to slides. Why are you trying to get rid of memory allocation failure messages? > Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> > --- > drivers/vhost/scsi.c | 24 +++++++----------------- > 1 file changed, 7 insertions(+), 17 deletions(-) > > diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c > index 650533916c19..49d07950e2e5 100644 > --- a/drivers/vhost/scsi.c > +++ b/drivers/vhost/scsi.c > @@ -417,5 +417,4 @@ vhost_scsi_allocate_evt(struct vhost_scsi *vs, > if (!evt) { > - vq_err(vq, "Failed to allocate vhost_scsi_evt\n"); #define vq_err(vq, fmt, ...) do { \ pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ if ((vq)->error_ctx) \ eventfd_signal((vq)->error_ctx, 1);\ } while (0) You silently dropped the eventfd_signal() call. Please explain.
>> Link: http://events.linuxfoundation.org/sites/events/files/slides/LCJ16-Refactor_Strings-WSang_0.pdf > > Please include an actual explanation for this change instead of linking > to slides. Do you care for a bit of code size reduction by removal of questionable error messages? > Why are you trying to get rid of memory allocation failure messages? Do you find information from a Linux allocation failure report sufficient for any function implementations here? >> +++ b/drivers/vhost/scsi.c >> @@ -417,5 +417,4 @@ vhost_scsi_allocate_evt(struct vhost_scsi *vs, >> if (!evt) { >> - vq_err(vq, "Failed to allocate vhost_scsi_evt\n"); > > #define vq_err(vq, fmt, ...) do { \ > pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ > if ((vq)->error_ctx) \ > eventfd_signal((vq)->error_ctx, 1);\ > } while (0) > > You silently dropped the eventfd_signal() call. Do you prefer to preserve this special error handling then? Regards, Markus
On Mon, May 22, 2017 at 12:50:39PM +0200, SF Markus Elfring wrote: > > Why are you trying to get rid of memory allocation failure messages? > > Do you find information from a Linux allocation failure report sufficient > for any function implementations here? If kmalloc() and friends guarantee to print a warning and backtrace on every allocation failure, then there's no need for error messages in callers. That seems like good justification that can go in the commit description, but I'm not sure if kmalloc() and friends guarantee to show a message (not just the first time, but for every failed allocation)? > >> +++ b/drivers/vhost/scsi.c > >> @@ -417,5 +417,4 @@ vhost_scsi_allocate_evt(struct vhost_scsi *vs, > >> if (!evt) { > >> - vq_err(vq, "Failed to allocate vhost_scsi_evt\n"); > > > > #define vq_err(vq, fmt, ...) do { \ > > pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ > > if ((vq)->error_ctx) \ > > eventfd_signal((vq)->error_ctx, 1);\ > > } while (0) > > > > You silently dropped the eventfd_signal() call. > > Do you prefer to preserve this special error handling then? Yes, please leave vq_err() calls. Stefan
>> Do you find information from a Linux allocation failure report sufficient >> for any function implementations here? > > If kmalloc() and friends guarantee to print a warning and backtrace on > every allocation failure, then there's no need for error messages in > callers. > > That seems like good justification that can go in the commit > description, but I'm not sure if kmalloc() and friends guarantee to show > a message (not just the first time, but for every failed allocation)? I am also looking for a more complete and easier accessible documentation for this aspect of the desired exception handling. How would we like to resolve any remaining open issues there? Regards, Markus
On Mon, May 22, 2017 at 12:23:20PM +0100, Stefan Hajnoczi wrote: > I'm not sure if kmalloc() and friends guarantee to show > a message (not just the first time, but for every failed allocation)? > It prints multiple times, but it's ratelimited. It can also be disabled using a config option. See slab_out_of_memory(). regards, dan carpenter
On Mon, May 22, 2017 at 03:38:33PM +0300, Dan Carpenter wrote: > On Mon, May 22, 2017 at 12:23:20PM +0100, Stefan Hajnoczi wrote: > > I'm not sure if kmalloc() and friends guarantee to show > > a message (not just the first time, but for every failed allocation)? > > > > It prints multiple times, but it's ratelimited. It can also be disabled > using a config option. > > See slab_out_of_memory(). Thanks! Stefan
On Mon, May 22, 2017 at 01:34:34PM +0200, SF Markus Elfring wrote: > >> Do you find information from a Linux allocation failure report sufficient > >> for any function implementations here? > > > > If kmalloc() and friends guarantee to print a warning and backtrace on > > every allocation failure, then there's no need for error messages in > > callers. > > > > That seems like good justification that can go in the commit > > description, but I'm not sure if kmalloc() and friends guarantee to show > > a message (not just the first time, but for every failed allocation)? > > I am also looking for a more complete and easier accessible documentation > for this aspect of the desired exception handling. > How would we like to resolve any remaining open issues there? No objection from me but please make sure to keep vq_err(). Stefan
> No objection from me but please make sure to keep vq_err().
How long should I wait before I may dare to send another variant for the
discussed update suggestion?
Which commit message would be acceptable then for this update step?
Regards,
Markus
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index 650533916c19..49d07950e2e5 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -417,5 +417,4 @@ vhost_scsi_allocate_evt(struct vhost_scsi *vs, if (!evt) { - vq_err(vq, "Failed to allocate vhost_scsi_evt\n"); vs->vs_events_missed = true; return NULL; } @@ -1722,21 +1721,15 @@ static int vhost_scsi_nexus_cb(struct se_portal_group *se_tpg, - if (!tv_cmd->tvc_sgl) { - pr_err("Unable to allocate tv_cmd->tvc_sgl\n"); + if (!tv_cmd->tvc_sgl) goto out; - } tv_cmd->tvc_upages = kzalloc(sizeof(struct page *) * VHOST_SCSI_PREALLOC_UPAGES, GFP_KERNEL); - if (!tv_cmd->tvc_upages) { - pr_err("Unable to allocate tv_cmd->tvc_upages\n"); + if (!tv_cmd->tvc_upages) goto out; - } tv_cmd->tvc_prot_sgl = kzalloc(sizeof(struct scatterlist) * VHOST_SCSI_PREALLOC_PROT_SGLS, GFP_KERNEL); - if (!tv_cmd->tvc_prot_sgl) { - pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n"); + if (!tv_cmd->tvc_prot_sgl) goto out; - } } return 0; out: @@ -1760,6 +1753,5 @@ static int vhost_scsi_make_nexus(struct vhost_scsi_tpg *tpg, if (!tv_nexus) { mutex_unlock(&tpg->tv_tpg_mutex); - pr_err("Unable to allocate struct vhost_scsi_nexus\n"); return -ENOMEM; } /* @@ -1961,7 +1953,6 @@ vhost_scsi_make_tpg(struct se_wwn *wwn, - if (!tpg) { - pr_err("Unable to allocate struct vhost_scsi_tpg"); + if (!tpg) return ERR_PTR(-ENOMEM); - } + mutex_init(&tpg->tv_tpg_mutex); INIT_LIST_HEAD(&tpg->tv_tpg_list); tpg->tport = tport; @@ -2015,7 +2006,6 @@ vhost_scsi_make_tport(struct target_fabric_configfs *tf, - if (!tport) { - pr_err("Unable to allocate struct vhost_scsi_tport"); + if (!tport) return ERR_PTR(-ENOMEM); - } + tport->tport_wwpn = wwpn; /* * Determine the emulated Protocol Identifier and Target Port Name