Messages in this thread | | | Date | Thu, 27 Nov 2008 15:07:55 +0100 | From | "stephane eranian" <> | Subject | Re: [patch 20/24] perfmon: system calls interface |
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Thomas,
On Thu, Nov 27, 2008 at 3:01 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > On Wed, 26 Nov 2008, eranian@googlemail.com wrote: > >> +asmlinkage long sys_pfm_write(int fd, int uflags, >> + int type, >> + void __user *ureq, >> + size_t sz) > >> +asmlinkage long sys_pfm_read(int fd, int uflags, >> + int type, >> + void __user *ureq, >> + size_t sz) > > After looking at both I did a diff of the two functions: > > --- r.c 2008-11-27 14:27:54.000000000 +0100 > +++ w.c 2008-11-27 14:27:52.000000000 +0100 > @@ -36,10 +36,12 @@ > ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED, &flags); > if (ret) > goto skip; > - > switch(type) { > + case PFM_RW_PMC: > + ret = __pfm_write_pmcs(ctx, req, count); > + break; > case PFM_RW_PMD: > - ret = __pfm_read_pmds(ctx, req, count); > + ret = __pfm_write_pmds(ctx, req, count); > break; > default: > PFM_DBG("invalid type=%d", type); > @@ -48,12 +50,13 @@ > skip: > spin_unlock_irqrestore(&ctx->lock, flags); > > - if (copy_to_user(ureq, req, sz)) > - ret = -EFAULT; > - > + /* > + * This function may be on the critical path. > + * We want to avoid the branch if unecessary. > + */ > if (fptr) > kfree(fptr); > error: > pfm_release_ctx_from_fd(&cookie); > return ret; > } > > Both read and write are multiplexing syscalls already and 90% of the > code is the same. > > case PFM_RD_PMC: > case PFM_RD_PMD: > case PFM_WR_PMC: > case PFM_WR_PMD: > > would make them the same and safe a syscall and duplicated code. > I am fine with that (BTW, there is no PFM_RD_PMC).
What about we call it pfm_rw_regs() ?
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